66 lines
4.0 KiB
Markdown
66 lines
4.0 KiB
Markdown
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# S/MIME
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This is a partial implementation of S/MIME 4.0 in golang.
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It consists of the following packages
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- asn1<sup>[1]</sup> - ASN.1 marshalling and unmarshalling [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/asn1)
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- b64 - Pretty base64 encoding for S/MIME (basically just the PEM body) [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/b64)
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- cms(cms/protocol)<sup>[2]</sup> - Cryptographic Message Syntax [rfc5652](https://tools.ietf.org/html/rfc5652)[](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/cms) [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/cms/protocol)
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- mime - Parsing for mime/multipart messages needed for S/MIME [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/mime)
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- oid<sup>[3]</sup> - ASN.1 object identifiers and related crypto [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/oid)
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- openssl - Shelled-out openssl for testing [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/openssl)
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- pki<sup>[4]</sup> - Creates x.509 pki for testing [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/pki)
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- smime Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 4.0 [rfc5751-bis-12](https://tools.ietf.org/html/draft-ietf-lamps-rfc5751-bis-12) [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/smime)
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- timestamp<sup>[5]</sup> - Time-Stamp Protocol (TSP) [rfc3161](https://tools.ietf.org/html/rfc3161) [](https://godoc.org/github.com/InfiniteLoopSpace/go_S-MIME/timestamp)
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It supports enveloped data with AES in CBC mode. Decryption also works with (3)DES. Authenticated-Enveloped-Data Content Type is also supported with AES-GCM and ChaCha20-Poly1305.
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This is covered in
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- Cryptographic Message Syntax (CMS) Authenticated-Enveloped-Data Content Type [rfc5083](https://tools.ietf.org/html/rfc5083)
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- Using ChaCha20-Poly1305 Authenticated Encryption in the Cryptographic Message Syntax (CMS) [rfc8103](https://tools.ietf.org/html/rfc8103)
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- Using AES-CCM and AES-GCM Authenticated Encryption in the Cryptographic Message Syntax (CMS) [rfc5084](https://tools.ietf.org/html/rfc 5084)
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## Examples
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### Encryption and decryption
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```go
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import "github.com/InfiniteLoopSpace/go_S-MIME/smime"
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// Alice
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mail := "From: Alice\nTo: Bob\n\nHello World!"
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SMIME, _ := smime.New()
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ciphertext, _ := SMIME.Encrypt([]byte(mail), []*x509.Certificate{Bobcert})
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// Bob
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BobkeyPair, _ := tls.LoadX509KeyPair("BobCert", "BobKey")
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SMIME, _ := smime.New(BobkeyPair)
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plaintext, _ := SMIME.Decrypt(ciphertext)
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```
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### Signing and verfication
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```go
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import "github.com/InfiniteLoopSpace/go_S-MIME/smime"
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// Alice
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AlicekeyPair, _ := tls.LoadX509KeyPair("AliceCert", "AliceKey")
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mail := "From: Alice\nTo: Bob\n\nHello World!"
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SMIME, _ := smime.New(AlicekeyPair)
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signedMsg, _ := SMIME.Sign([]byte(mail), []*x509.Certificate{Bobcert})
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// Bob
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SMIME, _ := smime.New()
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plaintext, _ := SMIME.Verify(signedMsg)
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```
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## Todo
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- Add S/MIME capabilities attributes
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- Add ECDH for encryption and decryption
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- Testing
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[1]: https://golang.org/pkg/encoding/asn1/
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[2]: https://github.com/mastahyeti/cms
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[3]: https://github.com/mastahyeti/cms
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[4]: https://github.com/mastahyeti/fakeca
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[5]: https://github.com/mastahyeti/cms
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