diff --git a/README.md b/README.md index 3a67d0d..9ab4303 100644 --- a/README.md +++ b/README.md @@ -59,6 +59,7 @@ Here are some highlights of go-mail's featureset: * [X] Custom error types for delivery errors * [X] Custom dial-context functions for more control over the connection (proxing, DNS hooking, etc.) * [X] Output a go-mail message as EML file and parse EML file into a go-mail message +* [X] S/MIME singed messages go-mail works like a programatic email client and provides lots of methods and functionalities you would consider standard in a MUA. diff --git a/dummy-chain-cert-ecdsa.pem b/dummy-chain-cert-ecdsa.pem new file mode 100644 index 0000000..5f9953c --- /dev/null +++ b/dummy-chain-cert-ecdsa.pem @@ -0,0 +1,26 @@ +-----BEGIN CERTIFICATE----- +MIICAzCCAaqgAwIBAgIUKNWGvPrlzuYHnP4m6nGe60LalYEwCgYIKoZIzj0EAwIw +ZTELMAkGA1UEBhMCVVMxDjAMBgNVBAgMBVN0YXRlMQ0wCwYDVQQHDARDaXR5MRcw +FQYDVQQKDA5JbnRlcm1lZGlhdGVDQTEeMBwGA1UEAwwVSW50ZXJtZWRpYXRlIEVD 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-0,0 +1,3 @@ +// SPDX-FileCopyrightText: Copyright (c) 2022-2024 The go-mail Authors +// +// SPDX-License-Identifier: MIT diff --git a/dummy-child-key-ecdsa.pem b/dummy-child-key-ecdsa.pem new file mode 100644 index 0000000..d2a1185 --- /dev/null +++ b/dummy-child-key-ecdsa.pem @@ -0,0 +1,8 @@ +-----BEGIN EC PARAMETERS----- +BggqhkjOPQMBBw== +-----END EC PARAMETERS----- +-----BEGIN EC PRIVATE KEY----- +MHcCAQEEIG20X4lI7vocwK2W3TYOW+XtQv/bwRWYknvAf2OK8WFJoAoGCCqGSM49 +AwEHoUQDQgAEzJEINkYWg2DlrPiJPzSoGXcMZuAc2oMFaLuke97osF7EYkICX4Qc +adNUtySOBPAIm6BX+Lj0Z0YdBxpfXFEfqQ== +-----END EC PRIVATE KEY----- \ No newline at end of file diff --git a/dummy-child-key-ecdsa.pem.license b/dummy-child-key-ecdsa.pem.license new file mode 100644 index 0000000..615ea2b --- /dev/null +++ b/dummy-child-key-ecdsa.pem.license @@ -0,0 +1,3 @@ +// SPDX-FileCopyrightText: Copyright (c) 2022-2024 The go-mail Authors +// +// SPDX-License-Identifier: MIT diff --git a/dummy-child-key-rsa.pem b/dummy-child-key-rsa.pem new file mode 100644 index 0000000..2a8639b --- /dev/null +++ b/dummy-child-key-rsa.pem @@ -0,0 +1,52 @@ +-----BEGIN PRIVATE KEY----- +MIIJQAIBADANBgkqhkiG9w0BAQEFAASCCSowggkmAgEAAoICAQCiLh0JJTRRBhmU +yiMKALHtTOK7T20Bwy+fG0SO6RlBc+hSuuX/n6znXcNgOBlQ2Gg3+p1on/bmcKnG +N/SCiVBLpROiwxg3blQbZ7B7Jors/MopGk0LIBOXHPtAuYbF4J6ND5Ol6sgeGjMn +omwRjZlfeuBlHY345MqvcwH/lPhOlKme+tWD+bsFh08NGS+3NdQGP6dA2bRVrPXh +LXStHEmqfKO9EMVLWv+77tYhZESD6XgnA8pWjbdr9jajCsrQWrCG3jqHtzHNxtwf +7xfRwwgoUhLEvue6SBVokZGVmDhvWdRt2sjtLcWWJCI3p7M+NXRt5qf6iu24wLBd +zIDuWfgooWu5vBzNZjSTh2if6R1as9BdwASwy1n2HMvqpzgA+f/rXDFbvVc7WIKi +uGzfWApBrL0qTCQBuSyepH0G4rQ2sJtI5U8QOKBO76nQJq5WDQgefBX4GDI8aJ6q +X+teQq1AqERUmLWx4WlTwxSo5X+d1jY9I8f61CRKVfIRgMvAZUhm2h6RnoVIgq7G +7W3HdC3RT/f758njI7oIv5bhiyqpgyKr3cYhmn0enjP+YtjY85m51q005qzRLfaT +YiwMR4qyJW4ZOEPntPs20CD+e+Pi2JLONpRdcsSrkqZusVjm5PFy2e5RyNFXTupU +H2KVrgTRHL3GG2KWF5PmBdkhQfGG1QIDAQABAoICAAL3IruL6/zP5DPZ9RkiL1m/ 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+6IYSiuwJOxDxZAmYuWYBtlvfWrOypEuWogZQv8C/zxDpkDSLAoIBAQDCrHxmh5NI +ksWQg0W6176uktwyypFBh8REE1VfCgoxJ84TVOQzEBiNQpRj/FUCe4e7ZElIAks+ +N9mh8smJLvHDVo7033NIfAZCfCbLve8uWSGAm5x+aKS7kG5gynojKT8vl0y88m5o +Nm+BfvpQKjb6n6jibZZRsQsyz5KBct+Gb9gyA81jjrFudBmYy9WZeEm6pjzQtkuq +I0xCbQFwB+It/utjz7okuAWk5fPU0LRqOvvEMJjf2DyvIK45FDsBF3zGlG8Zunnh +q3o28zXdQCvYxY5Ik8zRuSTTAQnaJ3/zUvqR2g3PoSF8d7/WSkzNK+ZhTANqPkq1 +SOg515Na9L4fAoH/Vc5+rLaoUcp4nHeJxoKq7E7M1DRuyFcxFD0IS/F57siB2ptA +MpFqDLIRbHGbfpdHNPR7cE3PXkqmQ08gW/YrROPNZp7+JV3/rRimrDRwwbnCjHP5 +lJJ1DkFYpyw3wY/AnqYsZkEaBcmwkU89icOR70MqOjPUPNmGM+nc0D+My1dVbc0j +FbUVfhsYzgtTIH6GXNjZATDgWTpmQqbH/W6kie1MoWQvj2Ik/VQ7ymCC4DBOwJDf +jZpCypZUMtQKjc083E4O77ZQlyabYN6bWHvfWdFxyziyl/1WXta1K7tiNhOu5Aff +yT92nPv7DrVQQY08v6NaxkBqShLcek/VfiOHAoIBAAtzd/HUAb7gG0zv29csv6On +Mdqu/bJcGRhkBr6LaaQQkleiw7WZOch9ZRsoiZuWxpooQQNCV0i2ok+bZ21xXHlA +CzKuPirCWN/qS6HqbzpLtePJw3/QCfiae1OoNV0CHRxgivwGSqZIpXB5lqHGiete +HuIKzi/J+T2o5hZFOo6+33m5rYgwqZE0tRi+zLa1U6juBF/GiVbdsqupm88KN6y6 +9P+vBWUJihN0D06yZBpnk82riiKIprEqe/URkpLy3b0UmCBsTqUOoCbBUabNEocy +v7bXMtIXUOo0gm7ZqfYXKHQR3oQbF0wqAxfI0RG0hl2syfqi5WQagMZ+PsW35cMC +ggEBAM6kIM/zUnNBFla+oTiPCyoII7nGmGz8dT9IhH0+6T5nNzG4O6D28A3MJcs1 +C3pfukCCeWOnDNCIQ7C9Hx5XcCDoI4eD6zCRy+7zXxn0FxYS+O6lczB2mXGE69Yp +n3qb7P4XqZYex3dT72czJUlY6nFB2e0FmyvSoez8fsH9Ws78c4JGO953klam/emA +Hc8nB3CyM8rb2JlM3WeQbmo+Sbi0Yvj+MWM2AnTXx0xyaFXKP4WGD8hAxTvf9tSX +3NAPVBXku4zRpvoXyyrcBVd9vwE0qBr3eWCuci8aDD6RAAJgb8HHX9RjRF/phFpY +S++xGnGHEUSEl7cWnO8k0RyJzzc= +-----END PRIVATE KEY----- diff --git a/dummy-child-key-rsa.pem.license b/dummy-child-key-rsa.pem.license new file mode 100644 index 0000000..615ea2b --- /dev/null +++ b/dummy-child-key-rsa.pem.license @@ -0,0 +1,3 @@ +// SPDX-FileCopyrightText: Copyright (c) 2022-2024 The go-mail Authors +// +// SPDX-License-Identifier: MIT diff --git a/encoding.go b/encoding.go index 9ed5666..8c38cea 100644 --- a/encoding.go +++ b/encoding.go @@ -171,17 +171,20 @@ const ( // TypeTextPlain represents the MIME type for plain text content. TypeTextPlain ContentType = "text/plain" + + // typeSMimeSigned represents the MIME type for S/MIME singed messages. + typeSMimeSigned ContentType = `application/pkcs7-signature; name="smime.p7s"` ) const ( // MIMEAlternative MIMEType represents a MIME multipart/alternative type, used for emails with multiple versions. MIMEAlternative MIMEType = "alternative" - // MIMEMixed MIMEType represents a MIME multipart/mixed type used for emails containing different types of content. MIMEMixed MIMEType = "mixed" - // MIMERelated MIMEType represents a MIME multipart/related type, used for emails with related content entities. MIMERelated MIMEType = "related" + // MIMESMime MIMEType represents a MIME multipart/signed type, used for siging emails with S/MIME. + MIMESMime MIMEType = `signed; protocol="application/pkcs7-signature"; micalg=sha-256` ) // String satisfies the fmt.Stringer interface for the Charset type. @@ -219,3 +222,8 @@ func (c ContentType) String() string { func (e Encoding) String() string { return string(e) } + +// String is a standard method to convert an MIMEType into a printable format +func (e MIMEType) String() string { + return string(e) +} diff --git a/encoding_test.go b/encoding_test.go index 14711b7..4c7778a 100644 --- a/encoding_test.go +++ b/encoding_test.go @@ -61,6 +61,11 @@ func TestContentType_String(t *testing.T) { "ContentType: application/pgp-encrypted", TypePGPEncrypted, "application/pgp-encrypted", }, + + { + "ContentType: pkcs7-signature", typeSMimeSigned, + `application/pkcs7-signature; name="smime.p7s"`, + }, } for _, tt := range tests { t.Run(tt.name, func(t *testing.T) { @@ -121,3 +126,24 @@ func TestCharset_String(t *testing.T) { }) } } + +// TestContentType_String tests the mime type method of the MIMEType object +func TestMimeType_String(t *testing.T) { + tests := []struct { + mt MIMEType + want string + }{ + {MIMEAlternative, "alternative"}, + {MIMEMixed, "mixed"}, + {MIMERelated, "related"}, + {MIMESMime, `signed; protocol="application/pkcs7-signature"; micalg=sha-256`}, + } + for _, tt := range tests { + t.Run(tt.mt.String(), func(t *testing.T) { + if tt.mt.String() != tt.want { + t.Errorf("wrong string for mime type returned. Expected: %s, got: %s", + tt.want, tt.mt.String()) + } + }) + } +} diff --git a/go.mod b/go.mod index 4fb64a8..84fc4bd 100644 --- a/go.mod +++ b/go.mod @@ -9,4 +9,4 @@ go 1.16 require ( golang.org/x/crypto v0.28.0 golang.org/x/text v0.19.0 -) +) \ No newline at end of file diff --git a/go.sum b/go.sum index 8e6bffc..2eb65e0 100644 --- a/go.sum +++ b/go.sum @@ -63,4 +63,4 @@ golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU= golang.org/x/tools v0.13.0/go.mod h1:HvlwmtVNQAhOuCjW7xxvovg8wbNq7LwfXh/k7wXUl58= golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk= -golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0= +golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0= \ No newline at end of file diff --git a/msg.go b/msg.go index 61feda1..7f5bbd9 100644 --- a/msg.go +++ b/msg.go @@ -7,6 +7,10 @@ package mail import ( "bytes" "context" + "crypto/ecdsa" + "crypto/rsa" + "crypto/tls" + "crypto/x509" "embed" "errors" "fmt" @@ -24,7 +28,7 @@ import ( ) var ( - // ErrNoFromAddress indicates that the FROM address is not set, which is required. + // ErrNoFromAddress should be used when a FROM address is requested but not set ErrNoFromAddress = errors.New("no FROM address set") // ErrNoRcptAddresses indicates that no recipient addresses have been set. @@ -144,6 +148,9 @@ type Msg struct { // // This can be useful in scenarios where headers are conditionally passed based on receipt - i. e. SMTP proxies. noDefaultUserAgent bool + + // SMime represents a middleware used to sign messages with S/MIME + sMime *SMime } // SendmailPath is the default system path to the sendmail binary - at least on standard Unix-like OS. @@ -333,8 +340,50 @@ func WithNoDefaultUserAgent() MsgOption { } } -// SetCharset sets or overrides the currently set encoding charset of the Msg. -// +// SignWithSMimeRSA configures the Msg to be signed with S/MIME +func (m *Msg) SignWithSMimeRSA(privateKey *rsa.PrivateKey, certificate *x509.Certificate, intermediateCertificate *x509.Certificate) error { + sMime, err := newSMimeWithRSA(privateKey, certificate, intermediateCertificate) + if err != nil { + return err + } + m.sMime = sMime + return nil +} + +// SignWithSMimeECDSA configures the Msg to be signed with S/MIME +func (m *Msg) SignWithSMimeECDSA(privateKey *ecdsa.PrivateKey, certificate *x509.Certificate, intermediateCertificate *x509.Certificate) error { + sMime, err := newSMimeWithECDSA(privateKey, certificate, intermediateCertificate) + if err != nil { + return err + } + m.sMime = sMime + return nil +} + +// SignWithTLSCertificate signs the Msg with the provided *tls.certificate. +func (m *Msg) SignWithTLSCertificate(keyPairTlS *tls.Certificate) error { + intermediateCertificate, err := x509.ParseCertificate(keyPairTlS.Certificate[1]) + if err != nil { + return fmt.Errorf("failed to parse intermediate certificate: %w", err) + } + + switch keyPairTlS.PrivateKey.(type) { + case *rsa.PrivateKey: + if intermediateCertificate == nil { + return m.SignWithSMimeRSA(keyPairTlS.PrivateKey.(*rsa.PrivateKey), keyPairTlS.Leaf, nil) + } + return m.SignWithSMimeRSA(keyPairTlS.PrivateKey.(*rsa.PrivateKey), keyPairTlS.Leaf, intermediateCertificate) + + case *ecdsa.PrivateKey: + if intermediateCertificate == nil { + return m.SignWithSMimeECDSA(keyPairTlS.PrivateKey.(*ecdsa.PrivateKey), keyPairTlS.Leaf, nil) + } + return m.SignWithSMimeECDSA(keyPairTlS.PrivateKey.(*ecdsa.PrivateKey), keyPairTlS.Leaf, intermediateCertificate) + default: + return fmt.Errorf("unsupported private key type: %T", keyPairTlS.PrivateKey) + } +} + // This method allows you to specify a character set for the email message. The charset is // important for ensuring that the content of the message is correctly interpreted by // mail clients. Common charset values include UTF-8, ISO-8859-1, and others. If a charset @@ -2115,6 +2164,38 @@ func (m *Msg) applyMiddlewares(msg *Msg) *Msg { return msg } +// signMessage sign the Msg with S/MIME +func (m *Msg) signMessage(msg *Msg) (*Msg, error) { + signedPart := msg.GetParts()[0] + body, err := signedPart.GetContent() + if err != nil { + return nil, err + } + + signaturePart, err := m.createSignaturePart(signedPart.GetEncoding(), signedPart.GetContentType(), signedPart.GetCharset(), body) + if err != nil { + return nil, err + } + + m.parts = append(m.parts, signaturePart) + + return m, err +} + +// createSignaturePart creates an additional part that be used for storing the S/MIME signature of the given body +func (m *Msg) createSignaturePart(encoding Encoding, contentType ContentType, charSet Charset, body []byte) (*Part, error) { + message := m.sMime.prepareMessage(encoding, contentType, charSet, body) + signedMessage, err := m.sMime.signMessage(message) + if err != nil { + return nil, err + } + + signaturePart := m.newPart(typeSMimeSigned, WithPartEncoding(EncodingB64), WithSMimeSinging()) + signaturePart.SetContent(*signedMessage) + + return signaturePart, nil +} + // WriteTo writes the formatted Msg into the given io.Writer and satisfies the io.WriterTo interface. // // This method writes the email message, including its headers, body, and attachments, to the provided @@ -2132,7 +2213,18 @@ func (m *Msg) applyMiddlewares(msg *Msg) *Msg { // - https://datatracker.ietf.org/doc/html/rfc5322 func (m *Msg) WriteTo(writer io.Writer) (int64, error) { mw := &msgWriter{writer: writer, charset: m.charset, encoder: m.encoder} - mw.writeMsg(m.applyMiddlewares(m)) + msg := m.applyMiddlewares(m) + + if m.hasSMime() { + signedMsg, err := m.signMessage(msg) + if err != nil { + return 0, err + } + msg = signedMsg + } + + mw.writeMsg(msg) + return mw.bytesWritten, mw.err } @@ -2496,7 +2588,7 @@ func (m *Msg) hasAlt() bool { count++ } } - return count > 1 && m.pgptype == 0 + return count > 1 && m.pgptype == 0 && !m.hasSMime() } // hasMixed returns true if the Msg has mixed parts. @@ -2514,6 +2606,11 @@ func (m *Msg) hasMixed() bool { return m.pgptype == 0 && ((len(m.parts) > 0 && len(m.attachments) > 0) || len(m.attachments) > 1) } +// hasSMime returns true if the Msg has should be signed with S/MIME +func (m *Msg) hasSMime() bool { + return m.sMime != nil +} + // hasRelated returns true if the Msg has related parts. // // This method checks whether the message contains related parts, such as inline embedded files diff --git a/msg_test.go b/msg_test.go index 7fcbd99..aa46f94 100644 --- a/msg_test.go +++ b/msg_test.go @@ -1907,6 +1907,39 @@ func TestMsg_hasAlt(t *testing.T) { } } +// TestMsg_hasAlt tests the hasAlt() method of the Msg with active S/MIME +func TestMsg_hasAltWithSMime(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + m := NewMsg() + m.SetBodyString(TypeTextPlain, "Plain") + m.AddAlternativeString(TypeTextHTML, "HTML") + if err := m.SignWithSMimeRSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to init smime configuration") + } + if m.hasAlt() { + t.Errorf("mail has alternative parts and S/MIME is active, but hasAlt() returned true") + } +} + +// TestMsg_hasSMime tests the hasSMime() method of the Msg +func TestMsg_hasSMime(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + m := NewMsg() + if err := m.SignWithSMimeRSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to init smime configuration") + } + m.SetBodyString(TypeTextPlain, "Plain") + if !m.hasSMime() { + t.Errorf("mail has smime configured but hasSMime() returned true") + } +} + // TestMsg_hasRelated tests the hasRelated() method of the Msg func TestMsg_hasRelated(t *testing.T) { m := NewMsg() @@ -1974,6 +2007,70 @@ func TestMsg_WriteToSkipMiddleware(t *testing.T) { } } +// TestMsg_WriteToWithSMIME tests the WriteTo() method of the Msg +func TestMsg_WriteToWithSMIME(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + + m := NewMsg() + m.Subject("This is a test") + m.SetBodyString(TypeTextPlain, "Plain") + if err := m.SignWithSMimeRSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to init smime configuration") + } + + wbuf := bytes.Buffer{} + if _, err = m.WriteTo(&wbuf); err != nil { + t.Errorf("WriteTo() failed: %s", err) + } + + result := wbuf.String() + boundary := result[strings.LastIndex(result, "--")-60 : strings.LastIndex(result, "--")] + if strings.Count(result, boundary) != 4 { + t.Errorf("WriteTo() failed. False number of boundaries found") + } + + parts := strings.Split(result, fmt.Sprintf("--%s", boundary)) + if len(parts) != 4 { + t.Errorf("WriteTo() failed. False number of parts found") + } + + preamble := parts[0] + if !strings.Contains(preamble, "MIME-Version: 1.0") { + t.Errorf("WriteTo() failed. Unable to find MIME-Version") + } + if !strings.Contains(preamble, "Subject: This is a test") { + t.Errorf("WriteTo() failed. Unable to find subject") + } + if !strings.Contains(preamble, fmt.Sprintf("Content-Type: multipart/signed; protocol=\"application/pkcs7-signature\"; micalg=sha-256;\r\n boundary=%s", boundary)) { + t.Errorf("WriteTo() failed. Unable to find Content-Type") + } + + signedData := parts[1] + if !strings.Contains(signedData, "Content-Transfer-Encoding: quoted-printable") { + t.Errorf("WriteTo() failed. Unable to find Content-Transfer-Encoding") + } + if !strings.Contains(signedData, "Content-Type: text/plain; charset=UTF-8") { + t.Errorf("WriteTo() failed. Unable to find Content-Type") + } + if !strings.Contains(signedData, "Plain") { + t.Errorf("WriteTo() failed. Unable to find Content") + } + + signature := parts[2] + if !strings.Contains(signature, "Content-Transfer-Encoding: base64") { + t.Errorf("WriteTo() failed. Unable to find Content-Transfer-Encoding") + } + if !strings.Contains(signature, `application/pkcs7-signature; name="smime.p7s"`) { + t.Errorf("WriteTo() failed. Unable to find Content-Type") + } + if strings.Contains(signature, "Plain") { + t.Errorf("WriteTo() failed. Unable to find signature") + } +} + // TestMsg_WriteTo_fails tests the WriteTo() method of the Msg but with a failing body writer function func TestMsg_WriteTo_fails(t *testing.T) { m := NewMsg() @@ -3246,6 +3343,66 @@ func TestNewMsgWithNoDefaultUserAgent(t *testing.T) { } } +// TestSignWithSMime_ValidRSAKeyPair tests WithSMimeSinging with given rsa key pair +func TestSignWithSMime_ValidRSAKeyPair(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + m := NewMsg() + if err := m.SignWithSMimeRSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to set sMime. Cause: %v", err) + } + if m.sMime.privateKey.rsa == nil { + t.Errorf("WithSMimeSinging() - no private key is given") + } + if m.sMime.certificate == nil { + t.Errorf("WithSMimeSinging() - no certificate is given") + } +} + +// TestSignWithSMime_ValidRSAKeyPair tests WithSMimeSinging with given ecdsa key pair +func TestSignWithSMime_ValidECDSAKeyPair(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyECDSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + m := NewMsg() + if err := m.SignWithSMimeECDSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to set sMime. Cause: %v", err) + } + if m.sMime.privateKey.ecdsa == nil { + t.Errorf("WithSMimeSinging() - no private key is given") + } + if m.sMime.certificate == nil { + t.Errorf("WithSMimeSinging() - no certificate is given") + } +} + +// TestSignWithSMime_InvalidPrivateKey tests WithSMimeSinging with given invalid private key +func TestSignWithSMime_InvalidPrivateKey(t *testing.T) { + m := NewMsg() + + err := m.SignWithSMimeRSA(nil, nil, nil) + if !errors.Is(err, ErrInvalidPrivateKey) { + t.Errorf("failed to pre-check SignWithSMime method values correctly: %s", err) + } +} + +// TestSignWithSMime_InvalidCertificate tests WithSMimeSinging with given invalid certificate +func TestSignWithSMime_InvalidCertificate(t *testing.T) { + privateKey, _, _, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + m := NewMsg() + + err = m.SignWithSMimeRSA(privateKey, nil, nil) + if !errors.Is(err, ErrInvalidCertificate) { + t.Errorf("failed to pre-check SignWithSMime method values correctly: %s", err) + } +} + // Fuzzing tests func FuzzMsg_Subject(f *testing.F) { f.Add("Testsubject") @@ -3273,3 +3430,84 @@ func FuzzMsg_From(f *testing.F) { m.Reset() }) } + +// TestMsg_createSignaturePart tests the Msg.createSignaturePart method +func TestMsg_createSignaturePart(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + m := NewMsg() + if err := m.SignWithSMimeRSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to init smime configuration") + } + body := []byte("This is the body") + part, err := m.createSignaturePart(EncodingQP, TypeTextPlain, CharsetUTF7, body) + if err != nil { + t.Errorf("createSignaturePart() method failed.") + } + + if part.GetEncoding() != EncodingB64 { + t.Errorf("createSignaturePart() method failed. Expected encoding: %s, got: %s", EncodingB64, part.GetEncoding()) + } + if part.GetContentType() != typeSMimeSigned { + t.Errorf("createSignaturePart() method failed. Expected content type: %s, got: %s", typeSMimeSigned, part.GetContentType()) + } + if part.GetCharset() != CharsetUTF8 { + t.Errorf("createSignaturePart() method failed. Expected charset: %s, got: %s", CharsetUTF8, part.GetCharset()) + } + if content, err := part.GetContent(); err != nil || len(content) == len(body) { + t.Errorf("createSignaturePart() method failed. Expected content should not be equal: %s, got: %s", body, part.GetEncoding()) + } +} + +// TestMsg_signMessage tests the Msg.signMessage method +func TestMsg_signMessage(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + body := []byte("This is the body") + m := NewMsg() + m.SetBodyString(TypeTextPlain, string(body)) + if err := m.SignWithSMimeRSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to init smime configuration") + } + msg, err := m.signMessage(m) + if err != nil { + t.Errorf("createSignaturePart() method failed.") + } + + parts := msg.GetParts() + if len(parts) != 2 { + t.Errorf("createSignaturePart() method failed. Expected 2 parts, got: %d", len(parts)) + } + + signedPart := parts[0] + if signedPart.GetEncoding() != EncodingQP { + t.Errorf("createSignaturePart() method failed. Expected encoding: %s, got: %s", EncodingB64, signedPart.GetEncoding()) + } + if signedPart.GetContentType() != TypeTextPlain { + t.Errorf("createSignaturePart() method failed. Expected content type: %s, got: %s", typeSMimeSigned, signedPart.GetContentType()) + } + if signedPart.GetCharset() != CharsetUTF8 { + t.Errorf("createSignaturePart() method failed. Expected charset: %s, got: %s", CharsetUTF8, signedPart.GetCharset()) + } + if content, err := signedPart.GetContent(); err != nil || len(content) != len(body) { + t.Errorf("createSignaturePart() method failed. Expected content should be equal: %s, got: %s", body, content) + } + + signaturePart := parts[1] + if signaturePart.GetEncoding() != EncodingB64 { + t.Errorf("createSignaturePart() method failed. Expected encoding: %s, got: %s", EncodingB64, signaturePart.GetEncoding()) + } + if signaturePart.GetContentType() != typeSMimeSigned { + t.Errorf("createSignaturePart() method failed. Expected content type: %s, got: %s", typeSMimeSigned, signaturePart.GetContentType()) + } + if signaturePart.GetCharset() != CharsetUTF8 { + t.Errorf("createSignaturePart() method failed. Expected charset: %s, got: %s", CharsetUTF8, signaturePart.GetCharset()) + } + if content, err := signaturePart.GetContent(); err != nil || len(content) == len(body) { + t.Errorf("createSignaturePart() method failed. Expected content should not be equal: %s, got: %s", body, signaturePart.GetEncoding()) + } +} diff --git a/msgwriter.go b/msgwriter.go index ed2b41e..331138c 100644 --- a/msgwriter.go +++ b/msgwriter.go @@ -128,6 +128,10 @@ func (mw *msgWriter) writeMsg(msg *Msg) { } } + if msg.hasSMime() { + mw.startMP(MIMESMime, msg.boundary) + mw.writeString(DoubleNewLine) + } if msg.hasMixed() { mw.startMP(MIMEMixed, msg.boundary) mw.writeString(DoubleNewLine) @@ -174,6 +178,10 @@ func (mw *msgWriter) writeMsg(msg *Msg) { if msg.hasMixed() { mw.stopMP() } + + if msg.hasSMime() { + mw.stopMP() + } } // writeGenHeader writes out all generic headers to the msgWriter. @@ -314,7 +322,7 @@ func (mw *msgWriter) addFiles(files []*File, isAttachment bool) { } if mw.err == nil { - mw.writeBody(file.Writer, encoding) + mw.writeBody(file.Writer, encoding, false) } } } @@ -347,7 +355,12 @@ func (mw *msgWriter) writePart(part *Part, charset Charset) { if partCharset.String() == "" { partCharset = charset } - contentType := fmt.Sprintf("%s; charset=%s", part.contentType, partCharset) + + contentType := part.contentType.String() + if !part.IsSMimeSigned() { + contentType = strings.Join([]string{contentType, "; charset=", partCharset.String()}, "") + } + contentTransferEnc := part.encoding.String() if mw.depth == 0 { mw.writeHeader(HeaderContentType, contentType) @@ -363,7 +376,7 @@ func (mw *msgWriter) writePart(part *Part, charset Charset) { mimeHeader.Add(string(HeaderContentTransferEnc), contentTransferEnc) mw.newPart(mimeHeader) } - mw.writeBody(part.writeFunc, part.encoding) + mw.writeBody(part.writeFunc, part.encoding, part.smime) } // writeString writes a string into the msgWriter's io.Writer interface. @@ -438,7 +451,8 @@ func (mw *msgWriter) writeHeader(key Header, values ...string) { // Parameters: // - writeFunc: A function that writes the body content to the given io.Writer. // - encoding: The encoding type to use when writing the content (e.g., base64, quoted-printable). -func (mw *msgWriter) writeBody(writeFunc func(io.Writer) (int64, error), encoding Encoding) { +// - singingWithSMime: Whether the msg should be signed with S/MIME or not. +func (mw *msgWriter) writeBody(writeFunc func(io.Writer) (int64, error), encoding Encoding, singingWithSMime bool) { var writer io.Writer var encodedWriter io.WriteCloser var n int64 @@ -453,12 +467,11 @@ func (mw *msgWriter) writeBody(writeFunc func(io.Writer) (int64, error), encodin lineBreaker := Base64LineBreaker{} lineBreaker.out = &writeBuffer - switch encoding { - case EncodingQP: + if encoding == EncodingQP { encodedWriter = quotedprintable.NewWriter(&writeBuffer) - case EncodingB64: + } else if encoding == EncodingB64 && !singingWithSMime { encodedWriter = base64.NewEncoder(base64.StdEncoding, &lineBreaker) - case NoEncoding: + } else if encoding == NoEncoding || singingWithSMime { _, err = writeFunc(&writeBuffer) if err != nil { mw.err = fmt.Errorf("bodyWriter function: %w", err) @@ -471,7 +484,7 @@ func (mw *msgWriter) writeBody(writeFunc func(io.Writer) (int64, error), encodin mw.bytesWritten += n } return - default: + } else { encodedWriter = quotedprintable.NewWriter(writer) } diff --git a/msgwriter_test.go b/msgwriter_test.go index a41e5d3..0379cd7 100644 --- a/msgwriter_test.go +++ b/msgwriter_test.go @@ -154,3 +154,42 @@ func TestMsgWriter_writeMsg_PGP(t *testing.T) { t.Errorf("writeMsg failed. Expected PGP encoding header but didn't find it in message output") } } + +// TestMsgWriter_writeMsg_SMime tests the writeMsg method of the msgWriter with S/MIME types set +func TestMsgWriter_writeMsg_SMime(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("failed to laod dummy crypto material. Cause: %v", err) + } + + m := NewMsg() + if err := m.SignWithSMimeRSA(privateKey, certificate, intermediateCertificate); err != nil { + t.Errorf("failed to init smime configuration") + } + _ = m.From(`"Toni Tester" `) + _ = m.To(`"Toni Receiver" `) + m.Subject("This is a subject") + m.SetBodyString(TypeTextPlain, "This is the body") + buf := bytes.Buffer{} + mw := &msgWriter{writer: &buf, charset: CharsetUTF8, encoder: mime.QEncoding} + mw.writeMsg(m) + ms := buf.String() + + if !strings.Contains(ms, "MIME-Version: 1.0") { + t.Errorf("writeMsg failed. Unable to find MIME-Version") + } + if !strings.Contains(ms, "Subject: This is a subject") { + t.Errorf("writeMsg failed. Unable to find subject") + } + if !strings.Contains(ms, "From: \"Toni Tester\" ") { + t.Errorf("writeMsg failed. Unable to find transmitter") + } + if !strings.Contains(ms, "To: \"Toni Receiver\" ") { + t.Errorf("writeMsg failed. Unable to find receiver") + } + + boundary := ms[strings.LastIndex(ms, "--")-60 : strings.LastIndex(ms, "--")] + if !strings.Contains(ms, fmt.Sprintf("Content-Type: multipart/signed; protocol=\"application/pkcs7-signature\"; micalg=sha-256;\r\n boundary=%s", boundary)) { + t.Errorf("writeMsg failed. Unable to find Content-Type") + } +} diff --git a/part.go b/part.go index 5be8059..3fab652 100644 --- a/part.go +++ b/part.go @@ -24,6 +24,7 @@ type Part struct { encoding Encoding isDeleted bool writeFunc func(io.Writer) (int64, error) + smime bool } // GetContent executes the WriteFunc of the Part and returns the content as a byte slice. @@ -94,6 +95,11 @@ func (p *Part) GetDescription() string { return p.description } +// IsSMimeSigned returns true if the Part should be singed with S/MIME +func (p *Part) IsSMimeSigned() bool { + return p.smime +} + // SetContent overrides the content of the Part with the given string. // // This function sets the content of the Part by creating a new writeFunc that writes the @@ -146,6 +152,11 @@ func (p *Part) SetDescription(description string) { p.description = description } +// SetIsSMimeSigned sets the flag for signing the Part with S/MIME +func (p *Part) SetIsSMimeSigned(smime bool) { + p.smime = smime +} + // SetWriteFunc overrides the WriteFunc of the Part. // // This function sets a new WriteFunc for the Part, replacing the existing one. The WriteFunc @@ -213,3 +224,10 @@ func WithPartContentDescription(description string) PartOption { p.description = description } } + +// WithSMimeSinging overrides the flag for signing the Part with S/MIME +func WithSMimeSinging() PartOption { + return func(p *Part) { + p.smime = true + } +} diff --git a/part_test.go b/part_test.go index a196986..c1a8ac7 100644 --- a/part_test.go +++ b/part_test.go @@ -102,6 +102,24 @@ func TestPart_WithPartContentDescription(t *testing.T) { } } +// TestPart_WithSMimeSinging tests the WithSMimeSinging method +func TestPart_WithSMimeSinging(t *testing.T) { + m := NewMsg() + part := m.newPart(TypeTextPlain, WithSMimeSinging()) + if part == nil { + t.Errorf("newPart() WithSMimeSinging() failed: no part returned") + return + } + if part.smime != true { + t.Errorf("newPart() WithSMimeSinging() failed: expected: %v, got: %v", true, part.smime) + } + part.smime = true + part.SetIsSMimeSigned(false) + if part.smime != false { + t.Errorf("newPart() SetIsSMimeSigned() failed: expected: %v, got: %v", false, part.smime) + } +} + // TestPartContentType tests Part.SetContentType func TestPart_SetContentType(t *testing.T) { tests := []struct { @@ -245,6 +263,33 @@ func TestPart_GetContentBroken(t *testing.T) { } } +// TestPart_IsSMimeSigned tests Part.IsSMimeSigned +func TestPart_IsSMimeSigned(t *testing.T) { + tests := []struct { + name string + want bool + }{ + {"smime:", true}, + {"smime:", false}, + } + for _, tt := range tests { + t.Run(tt.name, func(t *testing.T) { + m := NewMsg() + m.SetBodyString(TypeTextPlain, "This is a body!") + pl, err := getPartList(m) + if err != nil { + t.Errorf("failed: %s", err) + return + } + pl[0].SetIsSMimeSigned(tt.want) + smime := pl[0].IsSMimeSigned() + if smime != tt.want { + t.Errorf("SetContentType failed. Got: %v, expected: %v", smime, tt.want) + } + }) + } +} + // TestPart_SetWriteFunc tests Part.SetWriteFunc func TestPart_SetWriteFunc(t *testing.T) { c := "This is a test with ümläutß" diff --git a/pkcs7.go b/pkcs7.go new file mode 100644 index 0000000..70c2c24 --- /dev/null +++ b/pkcs7.go @@ -0,0 +1,388 @@ +// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors +// +// SPDX-License-Identifier: MIT + +package mail + +import ( + "bytes" + "crypto" + "crypto/rand" + "crypto/rsa" + "crypto/x509" + "crypto/x509/pkix" + "encoding/asn1" + "errors" + "fmt" + "math/big" + "sort" + "time" + + _ "crypto/sha1" // for crypto.SHA1 +) + +// PKCS7 Represents a PKCS7 structure +type PKCS7 struct { + Content []byte + Certificates []*x509.Certificate + CRLs []x509.RevocationList + Signers []signerInfo + raw interface{} +} + +type contentInfo struct { + ContentType asn1.ObjectIdentifier + Content asn1.RawValue `asn1:"explicit,optional,tag:0"` +} + +var ( + oidData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 1} + oidSignedData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 2} + oidAttributeContentType = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 3} + oidAttributeMessageDigest = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 4} + oidAttributeSigningTime = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 5} +) + +type signedData struct { + Version int `asn1:"default:1"` + DigestAlgorithmIdentifiers []pkix.AlgorithmIdentifier `asn1:"set"` + ContentInfo contentInfo + Certificates rawCertificates `asn1:"optional,tag:0"` + CRLs []x509.RevocationList `asn1:"optional,tag:1"` + SignerInfos []signerInfo `asn1:"set"` +} + +type rawCertificates struct { + Raw asn1.RawContent +} + +type attribute struct { + Type asn1.ObjectIdentifier + Value asn1.RawValue `asn1:"set"` +} + +type issuerAndSerial struct { + IssuerName asn1.RawValue + SerialNumber *big.Int +} + +// MessageDigestMismatchError is returned when the signer data digest does not +// match the computed digest for the contained content +type MessageDigestMismatchError struct { + ExpectedDigest []byte + ActualDigest []byte +} + +func (err *MessageDigestMismatchError) Error() string { + return fmt.Sprintf("pkcs7: Message digest mismatch\n\tExpected: %X\n\tActual : %X", err.ExpectedDigest, err.ActualDigest) +} + +type signerInfo struct { + Version int `asn1:"default:1"` + IssuerAndSerialNumber issuerAndSerial + DigestAlgorithm pkix.AlgorithmIdentifier + AuthenticatedAttributes []attribute `asn1:"optional,tag:0"` + DigestEncryptionAlgorithm pkix.AlgorithmIdentifier + EncryptedDigest []byte + UnauthenticatedAttributes []attribute `asn1:"optional,tag:1"` +} + +func (raw rawCertificates) Parse() ([]*x509.Certificate, error) { + if len(raw.Raw) == 0 { + return nil, nil + } + + var val asn1.RawValue + if _, err := asn1.Unmarshal(raw.Raw, &val); err != nil { + return nil, err + } + + return x509.ParseCertificates(val.Bytes) +} + +func marshalAttributes(attrs []attribute) ([]byte, error) { + encodedAttributes, err := asn1.Marshal(struct { + A []attribute `asn1:"set"` + }{A: attrs}) + if err != nil { + return nil, err + } + + // Remove the leading sequence octets + var raw asn1.RawValue + if _, err := asn1.Unmarshal(encodedAttributes, &raw); err != nil { + return nil, err + } + return raw.Bytes, nil +} + +var ( + oidDigestAlgorithmSHA1 = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 26} + oidSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 5} +) + +func getCertFromCertsByIssuerAndSerial(certs []*x509.Certificate, ias issuerAndSerial) *x509.Certificate { + for _, cert := range certs { + if isCertMatchForIssuerAndSerial(cert, ias) { + return cert + } + } + return nil +} + +// GetOnlySigner returns an x509.Certificate for the first signer of the signed +// data payload. If there are more or less than one signer, nil is returned +func (p7 *PKCS7) GetOnlySigner() *x509.Certificate { + if len(p7.Signers) != 1 { + return nil + } + signer := p7.Signers[0] + return getCertFromCertsByIssuerAndSerial(p7.Certificates, signer.IssuerAndSerialNumber) +} + +// ErrUnsupportedAlgorithm tells you when our quick dev assumptions have failed +var ErrUnsupportedAlgorithm = errors.New("pkcs7: cannot decrypt data: only RSA, DES, DES-EDE3, AES-256-CBC and AES-128-GCM supported") + +func isCertMatchForIssuerAndSerial(cert *x509.Certificate, ias issuerAndSerial) bool { + return cert.SerialNumber.Cmp(ias.SerialNumber) == 0 && bytes.Equal(cert.RawIssuer, ias.IssuerName.FullBytes) +} + +func unmarshalAttribute(attrs []attribute, attributeType asn1.ObjectIdentifier, out interface{}) error { + for _, attr := range attrs { + if attr.Type.Equal(attributeType) { + _, err := asn1.Unmarshal(attr.Value.Bytes, out) + return err + } + } + return errors.New("pkcs7: attribute type not in attributes") +} + +// UnmarshalSignedAttribute decodes a single attribute from the signer info +func (p7 *PKCS7) UnmarshalSignedAttribute(attributeType asn1.ObjectIdentifier, out interface{}) error { + sd, ok := p7.raw.(signedData) + if !ok { + return errors.New("pkcs7: payload is not signedData content") + } + if len(sd.SignerInfos) < 1 { + return errors.New("pkcs7: payload has no signers") + } + attributes := sd.SignerInfos[0].AuthenticatedAttributes + return unmarshalAttribute(attributes, attributeType, out) +} + +// SignedData is an opaque data structure for creating signed data payloads +type SignedData struct { + sd signedData + certs []*x509.Certificate + messageDigest []byte +} + +// Attribute represents a key value pair attribute. Value must be marshalable byte +// `encoding/asn1` +type Attribute struct { + Type asn1.ObjectIdentifier + Value interface{} +} + +// SignerInfoConfig are optional values to include when adding a signer +type SignerInfoConfig struct { + ExtraSignedAttributes []Attribute +} + +// newSignedData initializes a SignedData with content +func newSignedData(data []byte) (*SignedData, error) { + content, err := asn1.Marshal(data) + if err != nil { + return nil, err + } + ci := contentInfo{ + ContentType: oidData, + Content: asn1.RawValue{Class: 2, Tag: 0, Bytes: content, IsCompound: true}, + } + digAlg := pkix.AlgorithmIdentifier{ + Algorithm: oidDigestAlgorithmSHA1, + } + h := crypto.SHA1.New() + h.Write(data) + md := h.Sum(nil) + sd := signedData{ + ContentInfo: ci, + Version: 1, + DigestAlgorithmIdentifiers: []pkix.AlgorithmIdentifier{digAlg}, + } + return &SignedData{sd: sd, messageDigest: md}, nil +} + +type attributes struct { + types []asn1.ObjectIdentifier + values []interface{} +} + +// Add adds the attribute, maintaining insertion order +func (attrs *attributes) Add(attrType asn1.ObjectIdentifier, value interface{}) { + attrs.types = append(attrs.types, attrType) + attrs.values = append(attrs.values, value) +} + +type sortableAttribute struct { + SortKey []byte + Attribute attribute +} + +type attributeSet []sortableAttribute + +func (sa attributeSet) Len() int { + return len(sa) +} + +func (sa attributeSet) Less(i, j int) bool { + return bytes.Compare(sa[i].SortKey, sa[j].SortKey) < 0 +} + +func (sa attributeSet) Swap(i, j int) { + sa[i], sa[j] = sa[j], sa[i] +} + +func (sa attributeSet) attributes() []attribute { + attrs := make([]attribute, len(sa)) + for i, attr := range sa { + attrs[i] = attr.Attribute + } + return attrs +} + +func (attrs *attributes) forMarshaling() ([]attribute, error) { + sortables := make(attributeSet, len(attrs.types)) + for i := range sortables { + attrType := attrs.types[i] + attrValue := attrs.values[i] + asn1Value, err := asn1.Marshal(attrValue) + if err != nil { + return nil, err + } + attr := attribute{ + Type: attrType, + Value: asn1.RawValue{Tag: 17, IsCompound: true, Bytes: asn1Value}, // 17 == SET tag + } + encoded, err := asn1.Marshal(attr) + if err != nil { + return nil, err + } + sortables[i] = sortableAttribute{ + SortKey: encoded, + Attribute: attr, + } + } + sort.Sort(sortables) + return sortables.attributes(), nil +} + +// addSigner signs attributes about the content and adds certificate to payload +func (sd *SignedData) addSigner(cert *x509.Certificate, pkey crypto.PrivateKey, config SignerInfoConfig) error { + attrs := &attributes{} + attrs.Add(oidAttributeContentType, sd.sd.ContentInfo.ContentType) + attrs.Add(oidAttributeMessageDigest, sd.messageDigest) + attrs.Add(oidAttributeSigningTime, time.Now()) + for _, attr := range config.ExtraSignedAttributes { + attrs.Add(attr.Type, attr.Value) + } + finalAttrs, err := attrs.forMarshaling() + if err != nil { + return err + } + signature, err := signAttributes(finalAttrs, pkey, crypto.SHA1) + if err != nil { + return err + } + + ias, err := cert2issuerAndSerial(cert) + if err != nil { + return err + } + + signer := signerInfo{ + AuthenticatedAttributes: finalAttrs, + DigestAlgorithm: pkix.AlgorithmIdentifier{Algorithm: oidDigestAlgorithmSHA1}, + DigestEncryptionAlgorithm: pkix.AlgorithmIdentifier{Algorithm: oidSignatureSHA1WithRSA}, + IssuerAndSerialNumber: ias, + EncryptedDigest: signature, + Version: 1, + } + // create signature of signed attributes + sd.certs = append(sd.certs, cert) + sd.sd.SignerInfos = append(sd.sd.SignerInfos, signer) + return nil +} + +// addCertificate adds the certificate to the payload. Useful for parent certificates +func (sd *SignedData) addCertificate(cert *x509.Certificate) { + sd.certs = append(sd.certs, cert) +} + +// detach removes content from the signed data struct to make it a detached signature. +// This must be called right before Finish() +func (sd *SignedData) detach() { + sd.sd.ContentInfo = contentInfo{ContentType: oidData} +} + +// finish marshals the content and its signers +func (sd *SignedData) finish() ([]byte, error) { + sd.sd.Certificates = marshalCertificates(sd.certs) + inner, err := asn1.Marshal(sd.sd) + if err != nil { + return nil, err + } + outer := contentInfo{ + ContentType: oidSignedData, + Content: asn1.RawValue{Class: 2, Tag: 0, Bytes: inner, IsCompound: true}, + } + return asn1.Marshal(outer) +} + +func cert2issuerAndSerial(cert *x509.Certificate) (issuerAndSerial, error) { + var ias issuerAndSerial + // The issuer RDNSequence has to match exactly the sequence in the certificate + // We cannot use cert.Issuer.ToRDNSequence() here since it mangles the sequence + ias.IssuerName = asn1.RawValue{FullBytes: cert.RawIssuer} + ias.SerialNumber = cert.SerialNumber + + return ias, nil +} + +// signs the DER encoded form of the attributes with the private key +func signAttributes(attrs []attribute, pkey crypto.PrivateKey, hash crypto.Hash) ([]byte, error) { + attrBytes, err := marshalAttributes(attrs) + if err != nil { + return nil, err + } + h := hash.New() + h.Write(attrBytes) + hashed := h.Sum(nil) + switch priv := pkey.(type) { + case *rsa.PrivateKey: + return rsa.SignPKCS1v15(rand.Reader, priv, crypto.SHA1, hashed) + } + return nil, ErrUnsupportedAlgorithm +} + +// concats and wraps the certificates in the RawValue structure +func marshalCertificates(certs []*x509.Certificate) rawCertificates { + var buf bytes.Buffer + for _, cert := range certs { + buf.Write(cert.Raw) + } + rawCerts, _ := marshalCertificateBytes(buf.Bytes()) + return rawCerts +} + +// Even though, the tag & length are stripped out during marshalling the +// RawContent, we have to encode it into the RawContent. If its missing, +// then `asn1.Marshal()` will strip out the certificate wrapper instead. +func marshalCertificateBytes(certs []byte) (rawCertificates, error) { + val := asn1.RawValue{Bytes: certs, Class: 2, Tag: 0, IsCompound: true} + b, err := asn1.Marshal(val) + if err != nil { + return rawCertificates{}, err + } + return rawCertificates{Raw: b}, nil +} diff --git a/pkcs7_test.go b/pkcs7_test.go new file mode 100644 index 0000000..e84f8c1 --- /dev/null +++ b/pkcs7_test.go @@ -0,0 +1,123 @@ +// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors +// +// SPDX-License-Identifier: MIT + +package mail + +import ( + "crypto" + "crypto/rand" + "crypto/rsa" + "crypto/x509" + "crypto/x509/pkix" + "encoding/pem" + "fmt" + "math/big" + "os" + "testing" + "time" +) + +// TestSign_E2E tests S/MIME singing as e2e +func TestSign_E2E(t *testing.T) { + cert, err := createTestCertificate() + if err != nil { + t.Fatal(err) + } + content := []byte("Hello World") + for _, testDetach := range []bool{false, true} { + toBeSigned, err := newSignedData(content) + if err != nil { + t.Fatalf("Cannot initialize signed data: %s", err) + } + if err := toBeSigned.addSigner(cert.Certificate, cert.PrivateKey, SignerInfoConfig{}); err != nil { + t.Fatalf("Cannot add signer: %s", err) + } + if testDetach { + t.Log("Testing detached signature") + toBeSigned.detach() + } else { + t.Log("Testing attached signature") + } + signed, err := toBeSigned.finish() + if err != nil { + t.Fatalf("Cannot finish signing data: %s", err) + } + if err := pem.Encode(os.Stdout, &pem.Block{Type: "PKCS7", Bytes: signed}); err != nil { + t.Fatalf("Cannot write signed data: %s", err) + } + } +} + +type certKeyPair struct { + Certificate *x509.Certificate + PrivateKey *rsa.PrivateKey +} + +func createTestCertificate() (*certKeyPair, error) { + signer, err := createTestCertificateByIssuer("Eddard Stark", nil) + if err != nil { + return nil, err + } + fmt.Println("Created root cert") + if err := pem.Encode(os.Stdout, &pem.Block{Type: "CERTIFICATE", Bytes: signer.Certificate.Raw}); err != nil { + return nil, err + } + pair, err := createTestCertificateByIssuer("Jon Snow", signer) + if err != nil { + return nil, err + } + fmt.Println("Created signer cert") + if err := pem.Encode(os.Stdout, &pem.Block{Type: "CERTIFICATE", Bytes: pair.Certificate.Raw}); err != nil { + return nil, err + } + return pair, nil +} + +func createTestCertificateByIssuer(name string, issuer *certKeyPair) (*certKeyPair, error) { + priv, err := rsa.GenerateKey(rand.Reader, 1024) + if err != nil { + return nil, err + } + serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 32) + serialNumber, err := rand.Int(rand.Reader, serialNumberLimit) + if err != nil { + return nil, err + } + + template := x509.Certificate{ + SerialNumber: serialNumber, + SignatureAlgorithm: x509.SHA256WithRSA, + Subject: pkix.Name{ + CommonName: name, + Organization: []string{"Acme Co"}, + }, + NotBefore: time.Now(), + NotAfter: time.Now().AddDate(1, 0, 0), + KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature, + ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageEmailProtection}, + } + var issuerCert *x509.Certificate + var issuerKey crypto.PrivateKey + if issuer != nil { + issuerCert = issuer.Certificate + issuerKey = issuer.PrivateKey + } else { + template.IsCA = true + template.KeyUsage |= x509.KeyUsageCertSign + issuerCert = &template + issuerKey = priv + } + cert, err := x509.CreateCertificate(rand.Reader, &template, issuerCert, priv.Public(), issuerKey) + if err != nil { + return nil, err + } + leaf, err := x509.ParseCertificate(cert) + if err != nil { + return nil, err + } + return &certKeyPair{ + Certificate: leaf, + PrivateKey: priv, + }, nil +} diff --git a/smime.go b/smime.go new file mode 100644 index 0000000..da09713 --- /dev/null +++ b/smime.go @@ -0,0 +1,192 @@ +// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors +// +// SPDX-License-Identifier: MIT + +package mail + +import ( + "bytes" + "crypto" + "crypto/ecdsa" + "crypto/rsa" + "crypto/x509" + "encoding/pem" + "errors" + "fmt" + "strings" +) + +var ( + // ErrInvalidPrivateKey should be used if private key is invalid + ErrInvalidPrivateKey = errors.New("invalid private key") + + // ErrInvalidCertificate should be used if the certificate is invalid + ErrInvalidCertificate = errors.New("invalid certificate") +) + +// privateKeyHolder is the representation of a private key +type privateKeyHolder struct { + ecdsa *ecdsa.PrivateKey + rsa *rsa.PrivateKey +} + +// get returns the private key of the privateKeyHolder +func (p privateKeyHolder) get() crypto.PrivateKey { + if p.ecdsa != nil { + return p.ecdsa + } + return p.rsa +} + +// SMime is used to sign messages with S/MIME +type SMime struct { + privateKey privateKeyHolder + certificate *x509.Certificate + intermediateCertificate *x509.Certificate +} + +// newSMimeWithRSA construct a new instance of SMime with provided parameters +// privateKey as *rsa.PrivateKey +// certificate as *x509.Certificate +// intermediateCertificate (optional) as *x509.Certificate +func newSMimeWithRSA(privateKey *rsa.PrivateKey, certificate *x509.Certificate, intermediateCertificate *x509.Certificate) (*SMime, error) { + if privateKey == nil { + return nil, ErrInvalidPrivateKey + } + + if certificate == nil { + return nil, ErrInvalidCertificate + } + + return &SMime{ + privateKey: privateKeyHolder{rsa: privateKey}, + certificate: certificate, + intermediateCertificate: intermediateCertificate, + }, nil +} + +// newSMimeWithECDSA construct a new instance of SMime with provided parameters +// privateKey as *ecdsa.PrivateKey +// certificate as *x509.Certificate +// intermediateCertificate (optional) as *x509.Certificate +func newSMimeWithECDSA(privateKey *ecdsa.PrivateKey, certificate *x509.Certificate, intermediateCertificate *x509.Certificate) (*SMime, error) { + if privateKey == nil { + return nil, ErrInvalidPrivateKey + } + + if certificate == nil { + return nil, ErrInvalidCertificate + } + + return &SMime{ + privateKey: privateKeyHolder{ecdsa: privateKey}, + certificate: certificate, + intermediateCertificate: intermediateCertificate, + }, nil +} + +// signMessage signs the message with S/MIME +func (sm *SMime) signMessage(message string) (*string, error) { + lines := parseLines([]byte(message)) + toBeSigned := lines.bytesFromLines([]byte("\r\n")) + + signedData, err := newSignedData(toBeSigned) + if err != nil || signedData == nil { + return nil, fmt.Errorf("could not initialize signed data: %w", err) + } + + if err = signedData.addSigner(sm.certificate, sm.privateKey.get(), SignerInfoConfig{}); err != nil { + return nil, fmt.Errorf("could not add signer message: %w", err) + } + + if sm.intermediateCertificate != nil { + signedData.addCertificate(sm.intermediateCertificate) + } + + signedData.detach() + + signatureDER, err := signedData.finish() + if err != nil { + return nil, fmt.Errorf("could not finish signing: %w", err) + } + + pemMsg, err := encodeToPEM(signatureDER) + if err != nil { + return nil, fmt.Errorf("could not encode to PEM: %w", err) + } + + return pemMsg, nil +} + +// createMessage prepares the message that will be used for the sign method later +func (sm *SMime) prepareMessage(encoding Encoding, contentType ContentType, charset Charset, body []byte) string { + return fmt.Sprintf("Content-Transfer-Encoding: %v\r\nContent-Type: %v; charset=%v\r\n\r\n%v", encoding, contentType, charset, string(body)) +} + +// encodeToPEM uses the method pem.Encode from the standard library but cuts the typical PEM preamble +func encodeToPEM(msg []byte) (*string, error) { + block := &pem.Block{Bytes: msg} + + var arrayBuffer bytes.Buffer + if err := pem.Encode(&arrayBuffer, block); err != nil { + return nil, err + } + + r := arrayBuffer.String() + r = strings.TrimPrefix(r, "-----BEGIN -----") + r = strings.Trim(r, "\n") + r = strings.TrimSuffix(r, "-----END -----") + r = strings.Trim(r, "\n") + + return &r, nil +} + +// line is the representation of one line of the message that will be used for signing purposes +type line struct { + line []byte + endOfLine []byte +} + +// lines is the representation of a message that will be used for signing purposes +type lines []line + +// bytesFromLines creates the line representation with the given endOfLine char +func (ls lines) bytesFromLines(sep []byte) []byte { + var raw []byte + for i := range ls { + raw = append(raw, ls[i].line...) + if len(ls[i].endOfLine) != 0 && sep != nil { + raw = append(raw, sep...) + } else { + raw = append(raw, ls[i].endOfLine...) + } + } + return raw +} + +// parseLines constructs the lines representation of a given message +func parseLines(raw []byte) lines { + oneLine := line{raw, nil} + lines := lines{oneLine} + lines = lines.splitLine([]byte("\r\n")) + lines = lines.splitLine([]byte("\r")) + lines = lines.splitLine([]byte("\n")) + return lines +} + +// splitLine uses the given endOfLine to split the given line +func (ls lines) splitLine(sep []byte) lines { + nl := lines{} + for _, l := range ls { + split := bytes.Split(l.line, sep) + if len(split) > 1 { + for i := 0; i < len(split)-1; i++ { + nl = append(nl, line{split[i], sep}) + } + nl = append(nl, line{split[len(split)-1], l.endOfLine}) + } else { + nl = append(nl, l) + } + } + return nl +} diff --git a/smime_test.go b/smime_test.go new file mode 100644 index 0000000..d6fae44 --- /dev/null +++ b/smime_test.go @@ -0,0 +1,244 @@ +// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors +// +// SPDX-License-Identifier: MIT + +package mail + +import ( + "bytes" + "crypto/ecdsa" + "crypto/rsa" + "encoding/base64" + "fmt" + "strings" + "testing" +) + +func TestGet_RSA(t *testing.T) { + p := privateKeyHolder{ + ecdsa: nil, + rsa: &rsa.PrivateKey{}, + } + + if p.get() == nil { + t.Errorf("get() did not return the correct private key") + } +} + +func TestGet_ECDSA(t *testing.T) { + p := privateKeyHolder{ + ecdsa: &ecdsa.PrivateKey{}, + rsa: nil, + } + + if p.get() == nil { + t.Errorf("get() did not return the correct private key") + } +} + +// TestNewSMimeWithRSA tests the newSMime method with RSA crypto material +func TestNewSMimeWithRSA(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("Error getting dummy crypto material: %s", err) + } + + sMime, err := newSMimeWithRSA(privateKey, certificate, intermediateCertificate) + if err != nil { + t.Errorf("Error creating new SMime from keyPair: %s", err) + } + + if sMime.privateKey.rsa != privateKey { + t.Errorf("NewSMime() did not return the same private key") + } + if sMime.certificate != certificate { + t.Errorf("NewSMime() did not return the same certificate") + } + if sMime.intermediateCertificate != intermediateCertificate { + t.Errorf("NewSMime() did not return the same intermedidate certificate") + } +} + +// TestNewSMimeWithECDSA tests the newSMime method with ECDSA crypto material +func TestNewSMimeWithECDSA(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyECDSACryptoMaterial() + if err != nil { + t.Errorf("Error getting dummy crypto material: %s", err) + } + + sMime, err := newSMimeWithECDSA(privateKey, certificate, intermediateCertificate) + if err != nil { + t.Errorf("Error creating new SMime from keyPair: %s", err) + } + + if sMime.privateKey.ecdsa != privateKey { + t.Errorf("NewSMime() did not return the same private key") + } + if sMime.certificate != certificate { + t.Errorf("NewSMime() did not return the same certificate") + } + if sMime.intermediateCertificate != intermediateCertificate { + t.Errorf("NewSMime() did not return the same intermedidate certificate") + } +} + +// TestSign tests the sign method +func TestSign(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("Error getting dummy crypto material: %s", err) + } + + sMime, err := newSMimeWithRSA(privateKey, certificate, intermediateCertificate) + if err != nil { + t.Errorf("Error creating new SMime from keyPair: %s", err) + } + + message := "This is a test message" + singedMessage, err := sMime.signMessage(message) + if err != nil { + t.Errorf("Error creating singed message: %s", err) + } + + if *singedMessage == message { + t.Errorf("Sign() did not work") + } +} + +// TestPrepareMessage tests the createMessage method +func TestPrepareMessage(t *testing.T) { + privateKey, certificate, intermediateCertificate, err := getDummyRSACryptoMaterial() + if err != nil { + t.Errorf("Error getting dummy crypto material: %s", err) + } + + sMime, err := newSMimeWithRSA(privateKey, certificate, intermediateCertificate) + if err != nil { + t.Errorf("Error creating new SMime from keyPair: %s", err) + } + + encoding := EncodingB64 + contentType := TypeTextPlain + charset := CharsetUTF8 + body := []byte("This is the body!") + result := sMime.prepareMessage(encoding, contentType, charset, body) + + if !strings.Contains(result, encoding.String()) { + t.Errorf("createMessage() did not return the correct encoding") + } + if !strings.Contains(result, contentType.String()) { + t.Errorf("createMessage() did not return the correct contentType") + } + if !strings.Contains(result, string(body)) { + t.Errorf("createMessage() did not return the correct body") + } + if result != fmt.Sprintf("Content-Transfer-Encoding: %s\r\nContent-Type: %s; charset=%s\r\n\r\n%s", encoding, contentType, charset, string(body)) { + t.Errorf("createMessage() did not sucessfully create the message") + } +} + +// TestEncodeToPEM tests the encodeToPEM method +func TestEncodeToPEM(t *testing.T) { + message := []byte("This is a test message") + + pemMessage, err := encodeToPEM(message) + if err != nil { + t.Errorf("Error encoding message: %s", err) + } + + base64Encoded := base64.StdEncoding.EncodeToString(message) + if *pemMessage != base64Encoded { + t.Errorf("encodeToPEM() did not work") + } +} + +// TestBytesFromLines tests the bytesFromLines method +func TestBytesFromLines(t *testing.T) { + ls := lines{ + {line: []byte("Hello"), endOfLine: []byte("\n")}, + {line: []byte("World"), endOfLine: []byte("\n")}, + } + expected := []byte("Hello\nWorld\n") + + result := ls.bytesFromLines([]byte("\n")) + if !bytes.Equal(result, expected) { + t.Errorf("Expected %s, but got %s", expected, result) + } +} + +// FuzzBytesFromLines tests the bytesFromLines method with fuzzing +func FuzzBytesFromLines(f *testing.F) { + f.Add([]byte("Hello"), []byte("\n")) + f.Fuzz(func(t *testing.T, lineData, sep []byte) { + ls := lines{ + {line: lineData, endOfLine: sep}, + } + _ = ls.bytesFromLines(sep) + }) +} + +// TestParseLines tests the parseLines method +func TestParseLines(t *testing.T) { + input := []byte("Hello\r\nWorld\nHello\rWorld") + expected := lines{ + {line: []byte("Hello"), endOfLine: []byte("\r\n")}, + {line: []byte("World"), endOfLine: []byte("\n")}, + {line: []byte("Hello"), endOfLine: []byte("\r")}, + {line: []byte("World"), endOfLine: []byte("")}, + } + + result := parseLines(input) + if len(result) != len(expected) { + t.Errorf("Expected %d lines, but got %d", len(expected), len(result)) + } + + for i := range result { + if !bytes.Equal(result[i].line, expected[i].line) || !bytes.Equal(result[i].endOfLine, expected[i].endOfLine) { + t.Errorf("Line %d mismatch. Expected line: %s, endOfLine: %s, got line: %s, endOfLine: %s", + i, expected[i].line, expected[i].endOfLine, result[i].line, result[i].endOfLine) + } + } +} + +// FuzzParseLines tests the parseLines method with fuzzing +func FuzzParseLines(f *testing.F) { + f.Add([]byte("Hello\nWorld\r\nAnother\rLine")) + f.Fuzz(func(t *testing.T, input []byte) { + _ = parseLines(input) + }) +} + +// TestSplitLine tests the splitLine method +func TestSplitLine(t *testing.T) { + ls := lines{ + {line: []byte("Hello\r\nWorld\r\nAnotherLine"), endOfLine: []byte("")}, + } + expected := lines{ + {line: []byte("Hello"), endOfLine: []byte("\r\n")}, + {line: []byte("World"), endOfLine: []byte("\r\n")}, + {line: []byte("AnotherLine"), endOfLine: []byte("")}, + } + + result := ls.splitLine([]byte("\r\n")) + if len(result) != len(expected) { + t.Errorf("Expected %d lines, but got %d", len(expected), len(result)) + } + + for i := range result { + if !bytes.Equal(result[i].line, expected[i].line) || !bytes.Equal(result[i].endOfLine, expected[i].endOfLine) { + t.Errorf("Line %d mismatch. Expected line: %s, endOfLine: %s, got line: %s, endOfLine: %s", + i, expected[i].line, expected[i].endOfLine, result[i].line, result[i].endOfLine) + } + } +} + +// FuzzSplitLine tests the parseLsplitLineines method with fuzzing +func FuzzSplitLine(f *testing.F) { + f.Add([]byte("Hello\r\nWorld"), []byte("\r\n")) + f.Fuzz(func(t *testing.T, input, sep []byte) { + ls := lines{ + {line: input, endOfLine: []byte("")}, + } + _ = ls.splitLine(sep) + }) +} diff --git a/util_test.go b/util_test.go new file mode 100644 index 0000000..7640f62 --- /dev/null +++ b/util_test.go @@ -0,0 +1,64 @@ +// SPDX-FileCopyrightText: 2022-2023 The go-mail Authors +// +// SPDX-License-Identifier: MIT + +package mail + +import ( + "crypto/ecdsa" + "crypto/rsa" + "crypto/tls" + "crypto/x509" +) + +const ( + certRSAFilePath = "dummy-chain-cert-rsa.pem" + keyRSAFilePath = "dummy-child-key-rsa.pem" + + certECDSAFilePath = "dummy-chain-cert-ecdsa.pem" + keyECDSAFilePath = "dummy-child-key-ecdsa.pem" +) + +// getDummyRSACryptoMaterial loads a certificate (RSA) and the associated private key (ECDSA) form local disk for testing purposes +func getDummyRSACryptoMaterial() (*rsa.PrivateKey, *x509.Certificate, *x509.Certificate, error) { + keyPair, err := tls.LoadX509KeyPair(certRSAFilePath, keyRSAFilePath) + if err != nil { + return nil, nil, nil, err + } + + privateKey := keyPair.PrivateKey.(*rsa.PrivateKey) + + certificate, err := x509.ParseCertificate(keyPair.Certificate[0]) + if err != nil { + return nil, nil, nil, err + } + + intermediateCertificate, err := x509.ParseCertificate(keyPair.Certificate[1]) + if err != nil { + return nil, nil, nil, err + } + + return privateKey, certificate, intermediateCertificate, nil +} + +// getDummyECDSACryptoMaterial loads a certificate (ECDSA) and the associated private key (ECDSA) form local disk for testing purposes +func getDummyECDSACryptoMaterial() (*ecdsa.PrivateKey, *x509.Certificate, *x509.Certificate, error) { + keyPair, err := tls.LoadX509KeyPair(certECDSAFilePath, keyECDSAFilePath) + if err != nil { + return nil, nil, nil, err + } + + privateKey := keyPair.PrivateKey.(*ecdsa.PrivateKey) + + certificate, err := x509.ParseCertificate(keyPair.Certificate[0]) + if err != nil { + return nil, nil, nil, err + } + + intermediateCertificate, err := x509.ParseCertificate(keyPair.Certificate[1]) + if err != nil { + return nil, nil, nil, err + } + + return privateKey, certificate, intermediateCertificate, nil +}