Go JOSE

Package jose aims to provide an implementation of the Javascript Object Signing and Encryption set of standards. For the moment, it mainly focuses on encryption and signing based on the JSON Web Encryption and JSON Web Signature standards.

Disclaimer: This library contains encryption software that is subject to the U.S. Export Administration Regulations. You may not export, re-export, transfer or download this code or any part of it in violation of any United States law, directive or regulation. In particular this software may not be exported or re-exported in any form or on any media to Iran, North Sudan, Syria, Cuba, or North Korea, or to denied persons or entities mentioned on any US maintained blocked list.

Overview

The implementation follows the JSON Web Encryption standard (RFC 7516) and JSON Web Signature standard (RFC 7515). Tables of supported algorithms are shown below. The library supports both the compact and full serialization formats, and has optional support for multiple recipients. It also comes with a small command-line utility (jose-util) for dealing with JOSE messages in a shell.

Note: We use a forked version of the encoding/json package from the Go standard library which uses case-sensitive matching for member names (instead of case-insensitive matching). This is to avoid differences in interpretation of messages between go-jose and libraries in other languages. If you do not like this behavior, you can use the std_json build tag to disable it (though we do not recommend doing so).

Versions

We use gopkg.in for versioning.

Version 1 is the current stable version:

import "gopkg.in/square/go-jose.v1"

The interface for go-jose.v1 will remain backwards compatible. We're currently sketching out ideas for a new version, to clean up the interface a bit. If you have ideas or feature requests please let us know!

Supported algorithms

See below for a table of supported algorithms. Algorithm identifiers match the names in the JSON Web Algorithms standard where possible. The Godoc reference has a list of constants.

Key encryption	Algorithm identifier(s)
RSA-PKCS#1v1.5	RSA1_5
RSA-OAEP	RSA-OAEP, RSA-OAEP-256
AES key wrap	A128KW, A192KW, A256KW
AES-GCM key wrap	A128GCMKW, A192GCMKW, A256GCMKW
ECDH-ES + AES key wrap	ECDH-ES+A128KW, ECDH-ES+A192KW, ECDH-ES+A256KW
ECDH-ES (direct)	ECDH-ES¹
Direct encryption	dir¹

^{1. Not supported in multi-recipient mode}

Signing / MAC	Algorithm identifier(s)
RSASSA-PKCS#1v1.5	RS256, RS384, RS512
RSASSA-PSS	PS256, PS384, PS512
HMAC	HS256, HS384, HS512
ECDSA	ES256, ES384, ES512

Content encryption	Algorithm identifier(s)
AES-CBC+HMAC	A128CBC-HS256, A192CBC-HS384, A256CBC-HS512
AES-GCM	A128GCM, A192GCM, A256GCM

Compression	Algorithm identifiers(s)
DEFLATE (RFC 1951)	DEF

Supported key types

See below for a table of supported key types. These are understood by the library, and can be passed to corresponding functions such as NewEncrypter or NewSigner. Note that if you are creating a new encrypter or signer with a JsonWebKey, the key id of the JsonWebKey (if present) will be added to any resulting messages.

Algorithm(s)	Corresponding types
RSA	rsa.PublicKey, rsa.PrivateKey, *jose.JsonWebKey
ECDH, ECDSA	ecdsa.PublicKey, ecdsa.PrivateKey, *jose.JsonWebKey
AES, HMAC	[]byte, *jose.JsonWebKey

Examples

Encryption/decryption example using RSA:

// Generate a public/private key pair to use for this example. The library
// also provides two utility functions (LoadPublicKey and LoadPrivateKey)
// that can be used to load keys from PEM/DER-encoded data.
privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
	panic(err)
}

// Instantiate an encrypter using RSA-OAEP with AES128-GCM. An error would
// indicate that the selected algorithm(s) are not currently supported.
publicKey := &privateKey.PublicKey
encrypter, err := NewEncrypter(RSA_OAEP, A128GCM, publicKey)
if err != nil {
	panic(err)
}

// Encrypt a sample plaintext. Calling the encrypter returns an encrypted
// JWE object, which can then be serialized for output afterwards. An error
// would indicate a problem in an underlying cryptographic primitive.
var plaintext = []byte("Lorem ipsum dolor sit amet")
object, err := encrypter.Encrypt(plaintext)
if err != nil {
	panic(err)
}

// Serialize the encrypted object using the full serialization format.
// Alternatively you can also use the compact format here by calling
// object.CompactSerialize() instead.
serialized := object.FullSerialize()

// Parse the serialized, encrypted JWE object. An error would indicate that
// the given input did not represent a valid message.
object, err = ParseEncrypted(serialized)
if err != nil {
	panic(err)
}

// Now we can decrypt and get back our original plaintext. An error here
// would indicate the the message failed to decrypt, e.g. because the auth
// tag was broken or the message was tampered with.
decrypted, err := object.Decrypt(privateKey)
if err != nil {
	panic(err)
}

fmt.Printf(string(decrypted))
// output: Lorem ipsum dolor sit amet

Signing/verification example using RSA:

// Generate a public/private key pair to use for this example. The library
// also provides two utility functions (LoadPublicKey and LoadPrivateKey)
// that can be used to load keys from PEM/DER-encoded data.
privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
	panic(err)
}

// Instantiate a signer using RSASSA-PSS (SHA512) with the given private key.
signer, err := NewSigner(PS512, privateKey)
if err != nil {
	panic(err)
}

// Sign a sample payload. Calling the signer returns a protected JWS object,
// which can then be serialized for output afterwards. An error would
// indicate a problem in an underlying cryptographic primitive.
var payload = []byte("Lorem ipsum dolor sit amet")
object, err := signer.Sign(payload)
if err != nil {
	panic(err)
}

// Serialize the encrypted object using the full serialization format.
// Alternatively you can also use the compact format here by calling
// object.CompactSerialize() instead.
serialized := object.FullSerialize()

// Parse the serialized, protected JWS object. An error would indicate that
// the given input did not represent a valid message.
object, err = ParseSigned(serialized)
if err != nil {
	panic(err)
}

// Now we can verify the signature on the payload. An error here would
// indicate the the message failed to verify, e.g. because the signature was
// broken or the message was tampered with.
output, err := object.Verify(&privateKey.PublicKey)
if err != nil {
	panic(err)
}

fmt.Printf(string(output))
// output: Lorem ipsum dolor sit amet

More examples can be found in the Godoc reference for this package. The jose-util subdirectory also contains a small command-line utility which might be useful as an example.

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