diff options
Diffstat (limited to 'vendor/github.com/fullsailor/pkcs7/pkcs7.go')
| -rw-r--r-- | vendor/github.com/fullsailor/pkcs7/pkcs7.go | 962 |
1 files changed, 0 insertions, 962 deletions
diff --git a/vendor/github.com/fullsailor/pkcs7/pkcs7.go b/vendor/github.com/fullsailor/pkcs7/pkcs7.go deleted file mode 100644 index 0264466b4..000000000 --- a/vendor/github.com/fullsailor/pkcs7/pkcs7.go +++ /dev/null @@ -1,962 +0,0 @@ -// Package pkcs7 implements parsing and generation of some PKCS#7 structures. -package pkcs7 - -import ( - "bytes" - "crypto" - "crypto/aes" - "crypto/cipher" - "crypto/des" - "crypto/hmac" - "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 []pkix.CertificateList - Signers []signerInfo - raw interface{} -} - -type contentInfo struct { - ContentType asn1.ObjectIdentifier - Content asn1.RawValue `asn1:"explicit,optional,tag:0"` -} - -// ErrUnsupportedContentType is returned when a PKCS7 content is not supported. -// Currently only Data (1.2.840.113549.1.7.1), Signed Data (1.2.840.113549.1.7.2), -// and Enveloped Data are supported (1.2.840.113549.1.7.3) -var ErrUnsupportedContentType = errors.New("pkcs7: cannot parse data: unimplemented content type") - -type unsignedData []byte - -var ( - oidData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 1} - oidSignedData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 2} - oidEnvelopedData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 3} - oidSignedAndEnvelopedData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 4} - oidDigestedData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 5} - oidEncryptedData = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 6} - 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 []pkix.CertificateList `asn1:"optional,tag:1"` - SignerInfos []signerInfo `asn1:"set"` -} - -type rawCertificates struct { - Raw asn1.RawContent -} - -type envelopedData struct { - Version int - RecipientInfos []recipientInfo `asn1:"set"` - EncryptedContentInfo encryptedContentInfo -} - -type recipientInfo struct { - Version int - IssuerAndSerialNumber issuerAndSerial - KeyEncryptionAlgorithm pkix.AlgorithmIdentifier - EncryptedKey []byte -} - -type encryptedContentInfo struct { - ContentType asn1.ObjectIdentifier - ContentEncryptionAlgorithm pkix.AlgorithmIdentifier - EncryptedContent asn1.RawValue `asn1:"tag:0,optional"` -} - -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"` -} - -// Parse decodes a DER encoded PKCS7 package -func Parse(data []byte) (p7 *PKCS7, err error) { - if len(data) == 0 { - return nil, errors.New("pkcs7: input data is empty") - } - var info contentInfo - der, err := ber2der(data) - if err != nil { - return nil, err - } - rest, err := asn1.Unmarshal(der, &info) - if len(rest) > 0 { - err = asn1.SyntaxError{Msg: "trailing data"} - return - } - if err != nil { - return - } - - // fmt.Printf("--> Content Type: %s", info.ContentType) - switch { - case info.ContentType.Equal(oidSignedData): - return parseSignedData(info.Content.Bytes) - case info.ContentType.Equal(oidEnvelopedData): - return parseEnvelopedData(info.Content.Bytes) - } - return nil, ErrUnsupportedContentType -} - -func parseSignedData(data []byte) (*PKCS7, error) { - var sd signedData - asn1.Unmarshal(data, &sd) - certs, err := sd.Certificates.Parse() - if err != nil { - return nil, err - } - // fmt.Printf("--> Signed Data Version %d\n", sd.Version) - - var compound asn1.RawValue - var content unsignedData - - // The Content.Bytes maybe empty on PKI responses. - if len(sd.ContentInfo.Content.Bytes) > 0 { - if _, err := asn1.Unmarshal(sd.ContentInfo.Content.Bytes, &compound); err != nil { - return nil, err - } - } - // Compound octet string - if compound.IsCompound { - if _, err = asn1.Unmarshal(compound.Bytes, &content); err != nil { - return nil, err - } - } else { - // assuming this is tag 04 - content = compound.Bytes - } - return &PKCS7{ - Content: content, - Certificates: certs, - CRLs: sd.CRLs, - Signers: sd.SignerInfos, - raw: sd}, nil -} - -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 parseEnvelopedData(data []byte) (*PKCS7, error) { - var ed envelopedData - if _, err := asn1.Unmarshal(data, &ed); err != nil { - return nil, err - } - return &PKCS7{ - raw: ed, - }, nil -} - -// Verify checks the signatures of a PKCS7 object -// WARNING: Verify does not check signing time or verify certificate chains at -// this time. -func (p7 *PKCS7) Verify() (err error) { - if len(p7.Signers) == 0 { - return errors.New("pkcs7: Message has no signers") - } - for _, signer := range p7.Signers { - if err := verifySignature(p7, signer); err != nil { - return err - } - } - return nil -} - -func verifySignature(p7 *PKCS7, signer signerInfo) error { - signedData := p7.Content - hash, err := getHashForOID(signer.DigestAlgorithm.Algorithm) - if err != nil { - return err - } - if len(signer.AuthenticatedAttributes) > 0 { - // TODO(fullsailor): First check the content type match - var digest []byte - err := unmarshalAttribute(signer.AuthenticatedAttributes, oidAttributeMessageDigest, &digest) - if err != nil { - return err - } - h := hash.New() - h.Write(p7.Content) - computed := h.Sum(nil) - if !hmac.Equal(digest, computed) { - return &MessageDigestMismatchError{ - ExpectedDigest: digest, - ActualDigest: computed, - } - } - // TODO(fullsailor): Optionally verify certificate chain - // TODO(fullsailor): Optionally verify signingTime against certificate NotAfter/NotBefore - signedData, err = marshalAttributes(signer.AuthenticatedAttributes) - if err != nil { - return err - } - } - cert := getCertFromCertsByIssuerAndSerial(p7.Certificates, signer.IssuerAndSerialNumber) - if cert == nil { - return errors.New("pkcs7: No certificate for signer") - } - - algo := getSignatureAlgorithmFromAI(signer.DigestEncryptionAlgorithm) - if algo == x509.UnknownSignatureAlgorithm { - // I'm not sure what the spec here is, and the openssl sources were not - // helpful. But, this is what App Store receipts appear to do. - // The DigestEncryptionAlgorithm is just "rsaEncryption (PKCS #1)" - // But we're expecting a digest + encryption algorithm. So... we're going - // to determine an algorithm based on the DigestAlgorithm and this - // encryption algorithm. - if signer.DigestEncryptionAlgorithm.Algorithm.Equal(oidEncryptionAlgorithmRSA) { - algo = getRSASignatureAlgorithmForDigestAlgorithm(hash) - } - } - return cert.CheckSignature(algo, signedData, signer.EncryptedDigest) -} - -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 - asn1.Unmarshal(encodedAttributes, &raw) - return raw.Bytes, nil -} - -var ( - oidDigestAlgorithmSHA1 = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 26} - oidEncryptionAlgorithmRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 1} -) - -func getCertFromCertsByIssuerAndSerial(certs []*x509.Certificate, ias issuerAndSerial) *x509.Certificate { - for _, cert := range certs { - if isCertMatchForIssuerAndSerial(cert, ias) { - return cert - } - } - return nil -} - -func getHashForOID(oid asn1.ObjectIdentifier) (crypto.Hash, error) { - switch { - case oid.Equal(oidDigestAlgorithmSHA1): - return crypto.SHA1, nil - case oid.Equal(oidSHA256): - return crypto.SHA256, nil - } - return crypto.Hash(0), ErrUnsupportedAlgorithm -} - -func getRSASignatureAlgorithmForDigestAlgorithm(hash crypto.Hash) x509.SignatureAlgorithm { - for _, details := range signatureAlgorithmDetails { - if details.pubKeyAlgo == x509.RSA && details.hash == hash { - return details.algo - } - } - return x509.UnknownSignatureAlgorithm -} - -// 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") - -// ErrNotEncryptedContent is returned when attempting to Decrypt data that is not encrypted data -var ErrNotEncryptedContent = errors.New("pkcs7: content data is a decryptable data type") - -// Decrypt decrypts encrypted content info for recipient cert and private key -func (p7 *PKCS7) Decrypt(cert *x509.Certificate, pk crypto.PrivateKey) ([]byte, error) { - data, ok := p7.raw.(envelopedData) - if !ok { - return nil, ErrNotEncryptedContent - } - recipient := selectRecipientForCertificate(data.RecipientInfos, cert) - if recipient.EncryptedKey == nil { - return nil, errors.New("pkcs7: no enveloped recipient for provided certificate") - } - if priv := pk.(*rsa.PrivateKey); priv != nil { - var contentKey []byte - contentKey, err := rsa.DecryptPKCS1v15(rand.Reader, priv, recipient.EncryptedKey) - if err != nil { - return nil, err - } - return data.EncryptedContentInfo.decrypt(contentKey) - } - fmt.Printf("Unsupported Private Key: %v\n", pk) - return nil, ErrUnsupportedAlgorithm -} - -var oidEncryptionAlgorithmDESCBC = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 7} -var oidEncryptionAlgorithmDESEDE3CBC = asn1.ObjectIdentifier{1, 2, 840, 113549, 3, 7} -var oidEncryptionAlgorithmAES256CBC = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 1, 42} -var oidEncryptionAlgorithmAES128GCM = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 1, 6} -var oidEncryptionAlgorithmAES128CBC = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 1, 2} - -func (eci encryptedContentInfo) decrypt(key []byte) ([]byte, error) { - alg := eci.ContentEncryptionAlgorithm.Algorithm - if !alg.Equal(oidEncryptionAlgorithmDESCBC) && - !alg.Equal(oidEncryptionAlgorithmDESEDE3CBC) && - !alg.Equal(oidEncryptionAlgorithmAES256CBC) && - !alg.Equal(oidEncryptionAlgorithmAES128CBC) && - !alg.Equal(oidEncryptionAlgorithmAES128GCM) { - fmt.Printf("Unsupported Content Encryption Algorithm: %s\n", alg) - return nil, ErrUnsupportedAlgorithm - } - - // EncryptedContent can either be constructed of multple OCTET STRINGs - // or _be_ a tagged OCTET STRING - var cyphertext []byte - if eci.EncryptedContent.IsCompound { - // Complex case to concat all of the children OCTET STRINGs - var buf bytes.Buffer - cypherbytes := eci.EncryptedContent.Bytes - for { - var part []byte - cypherbytes, _ = asn1.Unmarshal(cypherbytes, &part) - buf.Write(part) - if cypherbytes == nil { - break - } - } - cyphertext = buf.Bytes() - } else { - // Simple case, the bytes _are_ the cyphertext - cyphertext = eci.EncryptedContent.Bytes - } - - var block cipher.Block - var err error - - switch { - case alg.Equal(oidEncryptionAlgorithmDESCBC): - block, err = des.NewCipher(key) - case alg.Equal(oidEncryptionAlgorithmDESEDE3CBC): - block, err = des.NewTripleDESCipher(key) - case alg.Equal(oidEncryptionAlgorithmAES256CBC): - fallthrough - case alg.Equal(oidEncryptionAlgorithmAES128GCM), alg.Equal(oidEncryptionAlgorithmAES128CBC): - block, err = aes.NewCipher(key) - } - - if err != nil { - return nil, err - } - - if alg.Equal(oidEncryptionAlgorithmAES128GCM) { - params := aesGCMParameters{} - paramBytes := eci.ContentEncryptionAlgorithm.Parameters.Bytes - - _, err := asn1.Unmarshal(paramBytes, ¶ms) - if err != nil { - return nil, err - } - - gcm, err := cipher.NewGCM(block) - if err != nil { - return nil, err - } - - if len(params.Nonce) != gcm.NonceSize() { - return nil, errors.New("pkcs7: encryption algorithm parameters are incorrect") - } - if params.ICVLen != gcm.Overhead() { - return nil, errors.New("pkcs7: encryption algorithm parameters are incorrect") - } - - plaintext, err := gcm.Open(nil, params.Nonce, cyphertext, nil) - if err != nil { - return nil, err - } - - return plaintext, nil - } - - iv := eci.ContentEncryptionAlgorithm.Parameters.Bytes - if len(iv) != block.BlockSize() { - return nil, errors.New("pkcs7: encryption algorithm parameters are malformed") - } - mode := cipher.NewCBCDecrypter(block, iv) - plaintext := make([]byte, len(cyphertext)) - mode.CryptBlocks(plaintext, cyphertext) - if plaintext, err = unpad(plaintext, mode.BlockSize()); err != nil { - return nil, err - } - return plaintext, nil -} - -func selectRecipientForCertificate(recipients []recipientInfo, cert *x509.Certificate) recipientInfo { - for _, recp := range recipients { - if isCertMatchForIssuerAndSerial(cert, recp.IssuerAndSerialNumber) { - return recp - } - } - return recipientInfo{} -} - -func isCertMatchForIssuerAndSerial(cert *x509.Certificate, ias issuerAndSerial) bool { - return cert.SerialNumber.Cmp(ias.SerialNumber) == 0 && bytes.Compare(cert.RawIssuer, ias.IssuerName.FullBytes) == 0 -} - -func pad(data []byte, blocklen int) ([]byte, error) { - if blocklen < 1 { - return nil, fmt.Errorf("invalid blocklen %d", blocklen) - } - padlen := blocklen - (len(data) % blocklen) - if padlen == 0 { - padlen = blocklen - } - pad := bytes.Repeat([]byte{byte(padlen)}, padlen) - return append(data, pad...), nil -} - -func unpad(data []byte, blocklen int) ([]byte, error) { - if blocklen < 1 { - return nil, fmt.Errorf("invalid blocklen %d", blocklen) - } - if len(data)%blocklen != 0 || len(data) == 0 { - return nil, fmt.Errorf("invalid data len %d", len(data)) - } - - // the last byte is the length of padding - padlen := int(data[len(data)-1]) - - // check padding integrity, all bytes should be the same - pad := data[len(data)-padlen:] - for _, padbyte := range pad { - if padbyte != byte(padlen) { - return nil, errors.New("invalid padding") - } - } - - return data[:len(data)-padlen], nil -} - -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) { - var 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 -} - -// DegenerateCertificate creates a signed data structure containing only the -// provided certificate or certificate chain. -func DegenerateCertificate(cert []byte) ([]byte, error) { - rawCert, err := marshalCertificateBytes(cert) - if err != nil { - return nil, err - } - emptyContent := contentInfo{ContentType: oidData} - sd := signedData{ - Version: 1, - ContentInfo: emptyContent, - Certificates: rawCert, - CRLs: []pkix.CertificateList{}, - } - content, err := asn1.Marshal(sd) - if err != nil { - return nil, err - } - signedContent := contentInfo{ - ContentType: oidSignedData, - Content: asn1.RawValue{Class: 2, Tag: 0, Bytes: content, IsCompound: true}, - } - return asn1.Marshal(signedContent) -} - -const ( - EncryptionAlgorithmDESCBC = iota - EncryptionAlgorithmAES128GCM -) - -// ContentEncryptionAlgorithm determines the algorithm used to encrypt the -// plaintext message. Change the value of this variable to change which -// algorithm is used in the Encrypt() function. -var ContentEncryptionAlgorithm = EncryptionAlgorithmDESCBC - -// ErrUnsupportedEncryptionAlgorithm is returned when attempting to encrypt -// content with an unsupported algorithm. -var ErrUnsupportedEncryptionAlgorithm = errors.New("pkcs7: cannot encrypt content: only DES-CBC and AES-128-GCM supported") - -const nonceSize = 12 - -type aesGCMParameters struct { - Nonce []byte `asn1:"tag:4"` - ICVLen int -} - -func encryptAES128GCM(content []byte) ([]byte, *encryptedContentInfo, error) { - // Create AES key and nonce - key := make([]byte, 16) - nonce := make([]byte, nonceSize) - - _, err := rand.Read(key) - if err != nil { - return nil, nil, err - } - - _, err = rand.Read(nonce) - if err != nil { - return nil, nil, err - } - - // Encrypt content - block, err := aes.NewCipher(key) - if err != nil { - return nil, nil, err - } - - gcm, err := cipher.NewGCM(block) - if err != nil { - return nil, nil, err - } - - ciphertext := gcm.Seal(nil, nonce, content, nil) - - // Prepare ASN.1 Encrypted Content Info - paramSeq := aesGCMParameters{ - Nonce: nonce, - ICVLen: gcm.Overhead(), - } - - paramBytes, err := asn1.Marshal(paramSeq) - if err != nil { - return nil, nil, err - } - - eci := encryptedContentInfo{ - ContentType: oidData, - ContentEncryptionAlgorithm: pkix.AlgorithmIdentifier{ - Algorithm: oidEncryptionAlgorithmAES128GCM, - Parameters: asn1.RawValue{ - Tag: asn1.TagSequence, - Bytes: paramBytes, - }, - }, - EncryptedContent: marshalEncryptedContent(ciphertext), - } - - return key, &eci, nil -} - -func encryptDESCBC(content []byte) ([]byte, *encryptedContentInfo, error) { - // Create DES key & CBC IV - key := make([]byte, 8) - iv := make([]byte, des.BlockSize) - _, err := rand.Read(key) - if err != nil { - return nil, nil, err - } - _, err = rand.Read(iv) - if err != nil { - return nil, nil, err - } - - // Encrypt padded content - block, err := des.NewCipher(key) - if err != nil { - return nil, nil, err - } - mode := cipher.NewCBCEncrypter(block, iv) - plaintext, err := pad(content, mode.BlockSize()) - cyphertext := make([]byte, len(plaintext)) - mode.CryptBlocks(cyphertext, plaintext) - - // Prepare ASN.1 Encrypted Content Info - eci := encryptedContentInfo{ - ContentType: oidData, - ContentEncryptionAlgorithm: pkix.AlgorithmIdentifier{ - Algorithm: oidEncryptionAlgorithmDESCBC, - Parameters: asn1.RawValue{Tag: 4, Bytes: iv}, - }, - EncryptedContent: marshalEncryptedContent(cyphertext), - } - - return key, &eci, nil -} - -// Encrypt creates and returns an envelope data PKCS7 structure with encrypted -// recipient keys for each recipient public key. -// -// The algorithm used to perform encryption is determined by the current value -// of the global ContentEncryptionAlgorithm package variable. By default, the -// value is EncryptionAlgorithmDESCBC. To use a different algorithm, change the -// value before calling Encrypt(). For example: -// -// ContentEncryptionAlgorithm = EncryptionAlgorithmAES128GCM -// -// TODO(fullsailor): Add support for encrypting content with other algorithms -func Encrypt(content []byte, recipients []*x509.Certificate) ([]byte, error) { - var eci *encryptedContentInfo - var key []byte - var err error - - // Apply chosen symmetric encryption method - switch ContentEncryptionAlgorithm { - case EncryptionAlgorithmDESCBC: - key, eci, err = encryptDESCBC(content) - - case EncryptionAlgorithmAES128GCM: - key, eci, err = encryptAES128GCM(content) - - default: - return nil, ErrUnsupportedEncryptionAlgorithm - } - - if err != nil { - return nil, err - } - - // Prepare each recipient's encrypted cipher key - recipientInfos := make([]recipientInfo, len(recipients)) - for i, recipient := range recipients { - encrypted, err := encryptKey(key, recipient) - if err != nil { - return nil, err - } - ias, err := cert2issuerAndSerial(recipient) - if err != nil { - return nil, err - } - info := recipientInfo{ - Version: 0, - IssuerAndSerialNumber: ias, - KeyEncryptionAlgorithm: pkix.AlgorithmIdentifier{ - Algorithm: oidEncryptionAlgorithmRSA, - }, - EncryptedKey: encrypted, - } - recipientInfos[i] = info - } - - // Prepare envelope content - envelope := envelopedData{ - EncryptedContentInfo: *eci, - Version: 0, - RecipientInfos: recipientInfos, - } - innerContent, err := asn1.Marshal(envelope) - if err != nil { - return nil, err - } - - // Prepare outer payload structure - wrapper := contentInfo{ - ContentType: oidEnvelopedData, - Content: asn1.RawValue{Class: 2, Tag: 0, IsCompound: true, Bytes: innerContent}, - } - - return asn1.Marshal(wrapper) -} - -func marshalEncryptedContent(content []byte) asn1.RawValue { - asn1Content, _ := asn1.Marshal(content) - return asn1.RawValue{Tag: 0, Class: 2, Bytes: asn1Content, IsCompound: true} -} - -func encryptKey(key []byte, recipient *x509.Certificate) ([]byte, error) { - if pub := recipient.PublicKey.(*rsa.PublicKey); pub != nil { - return rsa.EncryptPKCS1v15(rand.Reader, pub, key) - } - return nil, ErrUnsupportedAlgorithm -} |