gtsocial-umbx

httpsig.go (14435B)

---

 // Implements HTTP request and response signing and verification. Supports the
 // major MAC and asymmetric key signature algorithms. It has several safety
 // restrictions: One, none of the widely known non-cryptographically safe
 // algorithms are permitted; Two, the RSA SHA256 algorithms must be available in
 // the binary (and it should, barring export restrictions); Finally, the library
 // assumes either the 'Authorizationn' or 'Signature' headers are to be set (but
 // not both).
 package httpsig
 
 import (
 	"crypto"
 	"fmt"
 	"net/http"
 	"strings"
 	"time"
 
 	"golang.org/x/crypto/ssh"
 )
 
 // Algorithm specifies a cryptography secure algorithm for signing HTTP requests
 // and responses.
 type Algorithm string
 
 const (
 	// MAC-based algoirthms.
 	HMAC_SHA224      Algorithm = hmacPrefix + "-" + sha224String
 	HMAC_SHA256      Algorithm = hmacPrefix + "-" + sha256String
 	HMAC_SHA384      Algorithm = hmacPrefix + "-" + sha384String
 	HMAC_SHA512      Algorithm = hmacPrefix + "-" + sha512String
 	HMAC_RIPEMD160   Algorithm = hmacPrefix + "-" + ripemd160String
 	HMAC_SHA3_224    Algorithm = hmacPrefix + "-" + sha3_224String
 	HMAC_SHA3_256    Algorithm = hmacPrefix + "-" + sha3_256String
 	HMAC_SHA3_384    Algorithm = hmacPrefix + "-" + sha3_384String
 	HMAC_SHA3_512    Algorithm = hmacPrefix + "-" + sha3_512String
 	HMAC_SHA512_224  Algorithm = hmacPrefix + "-" + sha512_224String
 	HMAC_SHA512_256  Algorithm = hmacPrefix + "-" + sha512_256String
 	HMAC_BLAKE2S_256 Algorithm = hmacPrefix + "-" + blake2s_256String
 	HMAC_BLAKE2B_256 Algorithm = hmacPrefix + "-" + blake2b_256String
 	HMAC_BLAKE2B_384 Algorithm = hmacPrefix + "-" + blake2b_384String
 	HMAC_BLAKE2B_512 Algorithm = hmacPrefix + "-" + blake2b_512String
 	BLAKE2S_256      Algorithm = blake2s_256String
 	BLAKE2B_256      Algorithm = blake2b_256String
 	BLAKE2B_384      Algorithm = blake2b_384String
 	BLAKE2B_512      Algorithm = blake2b_512String
 	// RSA-based algorithms.
 	RSA_SHA1   Algorithm = rsaPrefix + "-" + sha1String
 	RSA_SHA224 Algorithm = rsaPrefix + "-" + sha224String
 	// RSA_SHA256 is the default algorithm.
 	RSA_SHA256    Algorithm = rsaPrefix + "-" + sha256String
 	RSA_SHA384    Algorithm = rsaPrefix + "-" + sha384String
 	RSA_SHA512    Algorithm = rsaPrefix + "-" + sha512String
 	RSA_RIPEMD160 Algorithm = rsaPrefix + "-" + ripemd160String
 	// ECDSA algorithms
 	ECDSA_SHA224    Algorithm = ecdsaPrefix + "-" + sha224String
 	ECDSA_SHA256    Algorithm = ecdsaPrefix + "-" + sha256String
 	ECDSA_SHA384    Algorithm = ecdsaPrefix + "-" + sha384String
 	ECDSA_SHA512    Algorithm = ecdsaPrefix + "-" + sha512String
 	ECDSA_RIPEMD160 Algorithm = ecdsaPrefix + "-" + ripemd160String
 	// ED25519 algorithms
 	// can only be SHA512
 	ED25519 Algorithm = ed25519Prefix
 
 	// Just because you can glue things together, doesn't mean they will
 	// work. The following options are not supported.
 	rsa_SHA3_224    Algorithm = rsaPrefix + "-" + sha3_224String
 	rsa_SHA3_256    Algorithm = rsaPrefix + "-" + sha3_256String
 	rsa_SHA3_384    Algorithm = rsaPrefix + "-" + sha3_384String
 	rsa_SHA3_512    Algorithm = rsaPrefix + "-" + sha3_512String
 	rsa_SHA512_224  Algorithm = rsaPrefix + "-" + sha512_224String
 	rsa_SHA512_256  Algorithm = rsaPrefix + "-" + sha512_256String
 	rsa_BLAKE2S_256 Algorithm = rsaPrefix + "-" + blake2s_256String
 	rsa_BLAKE2B_256 Algorithm = rsaPrefix + "-" + blake2b_256String
 	rsa_BLAKE2B_384 Algorithm = rsaPrefix + "-" + blake2b_384String
 	rsa_BLAKE2B_512 Algorithm = rsaPrefix + "-" + blake2b_512String
 )
 
 // HTTP Signatures can be applied to different HTTP headers, depending on the
 // expected application behavior.
 type SignatureScheme string
 
 const (
 	// Signature will place the HTTP Signature into the 'Signature' HTTP
 	// header.
 	Signature SignatureScheme = "Signature"
 	// Authorization will place the HTTP Signature into the 'Authorization'
 	// HTTP header.
 	Authorization SignatureScheme = "Authorization"
 )
 
 const (
 	// The HTTP Signatures specification uses the "Signature" auth-scheme
 	// for the Authorization header. This is coincidentally named, but not
 	// semantically the same, as the "Signature" HTTP header value.
 	signatureAuthScheme = "Signature"
 )
 
 // There are subtle differences to the values in the header. The Authorization
 // header has an 'auth-scheme' value that must be prefixed to the rest of the
 // key and values.
 func (s SignatureScheme) authScheme() string {
 	switch s {
 	case Authorization:
 		return signatureAuthScheme
 	default:
 		return ""
 	}
 }
 
 // Signers will sign HTTP requests or responses based on the algorithms and
 // headers selected at creation time.
 //
 // Signers are not safe to use between multiple goroutines.
 //
 // Note that signatures do set the deprecated 'algorithm' parameter for
 // backwards compatibility.
 type Signer interface {
 	// SignRequest signs the request using a private key. The public key id
 	// is used by the HTTP server to identify which key to use to verify the
 	// signature.
 	//
 	// If the Signer was created using a MAC based algorithm, then the key
 	// is expected to be of type []byte. If the Signer was created using an
 	// RSA based algorithm, then the private key is expected to be of type
 	// *rsa.PrivateKey.
 	//
 	// A Digest (RFC 3230) will be added to the request. The body provided
 	// must match the body used in the request, and is allowed to be nil.
 	// The Digest ensures the request body is not tampered with in flight,
 	// and if the signer is created to also sign the "Digest" header, the
 	// HTTP Signature will then ensure both the Digest and body are not both
 	// modified to maliciously represent different content.
 	SignRequest(pKey crypto.PrivateKey, pubKeyId string, r *http.Request, body []byte) error
 	// SignResponse signs the response using a private key. The public key
 	// id is used by the HTTP client to identify which key to use to verify
 	// the signature.
 	//
 	// If the Signer was created using a MAC based algorithm, then the key
 	// is expected to be of type []byte. If the Signer was created using an
 	// RSA based algorithm, then the private key is expected to be of type
 	// *rsa.PrivateKey.
 	//
 	// A Digest (RFC 3230) will be added to the response. The body provided
 	// must match the body written in the response, and is allowed to be
 	// nil. The Digest ensures the response body is not tampered with in
 	// flight, and if the signer is created to also sign the "Digest"
 	// header, the HTTP Signature will then ensure both the Digest and body
 	// are not both modified to maliciously represent different content.
 	SignResponse(pKey crypto.PrivateKey, pubKeyId string, r http.ResponseWriter, body []byte) error
 }
 
 // NewSigner creates a new Signer with the provided algorithm preferences to
 // make HTTP signatures. Only the first available algorithm will be used, which
 // is returned by this function along with the Signer. If none of the preferred
 // algorithms were available, then the default algorithm is used. The headers
 // specified will be included into the HTTP signatures.
 //
 // The Digest will also be calculated on a request's body using the provided
 // digest algorithm, if "Digest" is one of the headers listed.
 //
 // The provided scheme determines which header is populated with the HTTP
 // Signature.
 //
 // An error is returned if an unknown or a known cryptographically insecure
 // Algorithm is provided.
 func NewSigner(prefs []Algorithm, dAlgo DigestAlgorithm, headers []string, scheme SignatureScheme, expiresIn int64) (Signer, Algorithm, error) {
 	for _, pref := range prefs {
 		s, err := newSigner(pref, dAlgo, headers, scheme, expiresIn)
 		if err != nil {
 			continue
 		}
 		return s, pref, err
 	}
 	s, err := newSigner(defaultAlgorithm, dAlgo, headers, scheme, expiresIn)
 	return s, defaultAlgorithm, err
 }
 
 // Signers will sign HTTP requests or responses based on the algorithms and
 // headers selected at creation time.
 //
 // Signers are not safe to use between multiple goroutines.
 //
 // Note that signatures do set the deprecated 'algorithm' parameter for
 // backwards compatibility.
 type SSHSigner interface {
 	// SignRequest signs the request using ssh.Signer.
 	// The public key id is used by the HTTP server to identify which key to use
 	// to verify the signature.
 	//
 	// A Digest (RFC 3230) will be added to the request. The body provided
 	// must match the body used in the request, and is allowed to be nil.
 	// The Digest ensures the request body is not tampered with in flight,
 	// and if the signer is created to also sign the "Digest" header, the
 	// HTTP Signature will then ensure both the Digest and body are not both
 	// modified to maliciously represent different content.
 	SignRequest(pubKeyId string, r *http.Request, body []byte) error
 	// SignResponse signs the response using ssh.Signer. The public key
 	// id is used by the HTTP client to identify which key to use to verify
 	// the signature.
 	//
 	// A Digest (RFC 3230) will be added to the response. The body provided
 	// must match the body written in the response, and is allowed to be
 	// nil. The Digest ensures the response body is not tampered with in
 	// flight, and if the signer is created to also sign the "Digest"
 	// header, the HTTP Signature will then ensure both the Digest and body
 	// are not both modified to maliciously represent different content.
 	SignResponse(pubKeyId string, r http.ResponseWriter, body []byte) error
 }
 
 // NewwSSHSigner creates a new Signer using the specified ssh.Signer
 // At the moment only ed25519 ssh keys are supported.
 // The headers specified will be included into the HTTP signatures.
 //
 // The Digest will also be calculated on a request's body using the provided
 // digest algorithm, if "Digest" is one of the headers listed.
 //
 // The provided scheme determines which header is populated with the HTTP
 // Signature.
 func NewSSHSigner(s ssh.Signer, dAlgo DigestAlgorithm, headers []string, scheme SignatureScheme, expiresIn int64) (SSHSigner, Algorithm, error) {
 	sshAlgo := getSSHAlgorithm(s.PublicKey().Type())
 	if sshAlgo == "" {
 		return nil, "", fmt.Errorf("key type: %s not supported yet.", s.PublicKey().Type())
 	}
 
 	signer, err := newSSHSigner(s, sshAlgo, dAlgo, headers, scheme, expiresIn)
 	if err != nil {
 		return nil, "", err
 	}
 
 	return signer, sshAlgo, nil
 }
 
 func getSSHAlgorithm(pkType string) Algorithm {
 	switch {
 	case strings.HasPrefix(pkType, sshPrefix+"-"+ed25519Prefix):
 		return ED25519
 	case strings.HasPrefix(pkType, sshPrefix+"-"+rsaPrefix):
 		return RSA_SHA1
 	}
 
 	return ""
 }
 
 // Verifier verifies HTTP Signatures.
 //
 // It will determine which of the supported headers has the parameters
 // that define the signature.
 //
 // Verifiers are not safe to use between multiple goroutines.
 //
 // Note that verification ignores the deprecated 'algorithm' parameter.
 type Verifier interface {
 	// KeyId gets the public key id that the signature is signed with.
 	//
 	// Note that the application is expected to determine the algorithm
 	// used based on metadata or out-of-band information for this key id.
 	KeyId() string
 	// Verify accepts the public key specified by KeyId and returns an
 	// error if verification fails or if the signature is malformed. The
 	// algorithm must be the one used to create the signature in order to
 	// pass verification. The algorithm is determined based on metadata or
 	// out-of-band information for the key id.
 	//
 	// If the signature was created using a MAC based algorithm, then the
 	// key is expected to be of type []byte. If the signature was created
 	// using an RSA based algorithm, then the public key is expected to be
 	// of type *rsa.PublicKey.
 	Verify(pKey crypto.PublicKey, algo Algorithm) error
 }
 
 const (
 	// host is treated specially because golang may not include it in the
 	// request header map on the server side of a request.
 	hostHeader = "Host"
 )
 
 // NewVerifier verifies the given request. It returns an error if the HTTP
 // Signature parameters are not present in any headers, are present in more than
 // one header, are malformed, or are missing required parameters. It ignores
 // unknown HTTP Signature parameters.
 func NewVerifier(r *http.Request) (Verifier, error) {
 	h := r.Header
 	if _, hasHostHeader := h[hostHeader]; len(r.Host) > 0 && !hasHostHeader {
 		h[hostHeader] = []string{r.Host}
 	}
 	return newVerifier(h, func(h http.Header, toInclude []string, created int64, expires int64) (string, error) {
 		return signatureString(h, toInclude, addRequestTarget(r), created, expires)
 	})
 }
 
 // NewResponseVerifier verifies the given response. It returns errors under the
 // same conditions as NewVerifier.
 func NewResponseVerifier(r *http.Response) (Verifier, error) {
 	return newVerifier(r.Header, func(h http.Header, toInclude []string, created int64, expires int64) (string, error) {
 		return signatureString(h, toInclude, requestTargetNotPermitted, created, expires)
 	})
 }
 
 func newSSHSigner(sshSigner ssh.Signer, algo Algorithm, dAlgo DigestAlgorithm, headers []string, scheme SignatureScheme, expiresIn int64) (SSHSigner, error) {
 	var expires, created int64 = 0, 0
 
 	if expiresIn != 0 {
 		created = time.Now().Unix()
 		expires = created + expiresIn
 	}
 
 	s, err := signerFromSSHSigner(sshSigner, string(algo))
 	if err != nil {
 		return nil, fmt.Errorf("no crypto implementation available for ssh algo %q", algo)
 	}
 
 	a := &asymmSSHSigner{
 		asymmSigner: &asymmSigner{
 			s:            s,
 			dAlgo:        dAlgo,
 			headers:      headers,
 			targetHeader: scheme,
 			prefix:       scheme.authScheme(),
 			created:      created,
 			expires:      expires,
 		},
 	}
 
 	return a, nil
 }
 
 func newSigner(algo Algorithm, dAlgo DigestAlgorithm, headers []string, scheme SignatureScheme, expiresIn int64) (Signer, error) {
 
 	var expires, created int64 = 0, 0
 	if expiresIn != 0 {
 		created = time.Now().Unix()
 		expires = created + expiresIn
 	}
 
 	s, err := signerFromString(string(algo))
 	if err == nil {
 		a := &asymmSigner{
 			s:            s,
 			dAlgo:        dAlgo,
 			headers:      headers,
 			targetHeader: scheme,
 			prefix:       scheme.authScheme(),
 			created:      created,
 			expires:      expires,
 		}
 		return a, nil
 	}
 	m, err := macerFromString(string(algo))
 	if err != nil {
 		return nil, fmt.Errorf("no crypto implementation available for %q", algo)
 	}
 	c := &macSigner{
 		m:            m,
 		dAlgo:        dAlgo,
 		headers:      headers,
 		targetHeader: scheme,
 		prefix:       scheme.authScheme(),
 		created:      created,
 		expires:      expires,
 	}
 	return c, nil
 }