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pkcs7.js
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pkcs7.js
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/**
* Javascript implementation of PKCS#7 v1.5.
*
* @author Stefan Siegl
* @author Dave Longley
*
* Copyright (c) 2012 Stefan Siegl <[email protected]>
* Copyright (c) 2012-2015 Digital Bazaar, Inc.
*
* Currently this implementation only supports ContentType of EnvelopedData,
* EncryptedData, or SignedData at the root level. The top level elements may
* contain only a ContentInfo of ContentType Data, i.e. plain data. Further
* nesting is not (yet) supported.
*
* The Forge validators for PKCS #7's ASN.1 structures are available from
* a separate file pkcs7asn1.js, since those are referenced from other
* PKCS standards like PKCS #12.
*/
var forge = require('./forge');
require('./aes');
require('./asn1');
require('./des');
require('./oids');
require('./pem');
require('./pkcs7asn1');
require('./random');
require('./util');
require('./x509');
// shortcut for ASN.1 API
var asn1 = forge.asn1;
// shortcut for PKCS#7 API
var p7 = module.exports = forge.pkcs7 = forge.pkcs7 || {};
/**
* Converts a PKCS#7 message from PEM format.
*
* @param pem the PEM-formatted PKCS#7 message.
*
* @return the PKCS#7 message.
*/
p7.messageFromPem = function(pem) {
var msg = forge.pem.decode(pem)[0];
if(msg.type !== 'PKCS7') {
var error = new Error('Could not convert PKCS#7 message from PEM; PEM ' +
'header type is not "PKCS#7".');
error.headerType = msg.type;
throw error;
}
if(msg.procType && msg.procType.type === 'ENCRYPTED') {
throw new Error('Could not convert PKCS#7 message from PEM; PEM is encrypted.');
}
// convert DER to ASN.1 object
var obj = asn1.fromDer(msg.body);
return p7.messageFromAsn1(obj);
};
/**
* Converts a PKCS#7 message to PEM format.
*
* @param msg The PKCS#7 message object
* @param maxline The maximum characters per line, defaults to 64.
*
* @return The PEM-formatted PKCS#7 message.
*/
p7.messageToPem = function(msg, maxline) {
// convert to ASN.1, then DER, then PEM-encode
var pemObj = {
type: 'PKCS7',
body: asn1.toDer(msg.toAsn1()).getBytes()
};
return forge.pem.encode(pemObj, {maxline: maxline});
};
/**
* Converts a PKCS#7 message from an ASN.1 object.
*
* @param obj the ASN.1 representation of a ContentInfo.
*
* @return the PKCS#7 message.
*/
p7.messageFromAsn1 = function(obj) {
// validate root level ContentInfo and capture data
var capture = {};
var errors = [];
if(!asn1.validate(obj, p7.asn1.contentInfoValidator, capture, errors)) {
var error = new Error('Cannot read PKCS#7 message. ' +
'ASN.1 object is not an PKCS#7 ContentInfo.');
error.errors = errors;
throw error;
}
var contentType = asn1.derToOid(capture.contentType);
var msg;
switch(contentType) {
case forge.pki.oids.envelopedData:
msg = p7.createEnvelopedData();
break;
case forge.pki.oids.encryptedData:
msg = p7.createEncryptedData();
break;
case forge.pki.oids.signedData:
msg = p7.createSignedData();
break;
default:
throw new Error('Cannot read PKCS#7 message. ContentType with OID ' +
contentType + ' is not (yet) supported.');
}
msg.fromAsn1(capture.content.value[0]);
return msg;
};
p7.createSignedData = function() {
var msg = null;
msg = {
type: forge.pki.oids.signedData,
version: 1,
certificates: [],
crls: [],
// TODO: add json-formatted signer stuff here?
signers: [],
// populated during sign()
digestAlgorithmIdentifiers: [],
contentInfo: null,
signerInfos: [],
fromAsn1: function(obj) {
// validate SignedData content block and capture data.
_fromAsn1(msg, obj, p7.asn1.signedDataValidator);
msg.certificates = [];
msg.crls = [];
msg.digestAlgorithmIdentifiers = [];
msg.contentInfo = null;
msg.signerInfos = [];
if(msg.rawCapture.certificates) {
var certs = msg.rawCapture.certificates.value;
for(var i = 0; i < certs.length; ++i) {
msg.certificates.push(forge.pki.certificateFromAsn1(certs[i]));
}
}
// TODO: parse crls
msg.contentInfo = msg.rawCapture.contentInfo;
msg.signerInfos = msg.rawCapture.signerInfos;
if(msg.signerInfos) {
msg.signers = _signersFromAsn1(msg.signerInfos);
}
},
toAsn1: function() {
// degenerate case with no content
if(!msg.contentInfo) {
msg.sign();
}
var certs = [];
for(var i = 0; i < msg.certificates.length; ++i) {
certs.push(forge.pki.certificateToAsn1(msg.certificates[i]));
}
var crls = [];
// TODO: implement CRLs
// [0] SignedData
var signedData = asn1.create(asn1.Class.CONTEXT_SPECIFIC, 0, true, [
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// Version
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.INTEGER, false,
asn1.integerToDer(msg.version).getBytes()),
// DigestAlgorithmIdentifiers
asn1.create(
asn1.Class.UNIVERSAL, asn1.Type.SET, true,
msg.digestAlgorithmIdentifiers),
// ContentInfo
msg.contentInfo
])
]);
if(certs.length > 0) {
// [0] IMPLICIT ExtendedCertificatesAndCertificates OPTIONAL
signedData.value[0].value.push(
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 0, true, certs));
}
if(crls.length > 0) {
// [1] IMPLICIT CertificateRevocationLists OPTIONAL
signedData.value[0].value.push(
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 1, true, crls));
}
// SignerInfos
signedData.value[0].value.push(
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SET, true,
msg.signerInfos));
// ContentInfo
return asn1.create(
asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// ContentType
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OID, false,
asn1.oidToDer(msg.type).getBytes()),
// [0] SignedData
signedData
]);
},
/**
* Add (another) entity to list of signers.
*
* Note: If authenticatedAttributes are provided, then, per RFC 2315,
* they must include at least two attributes: content type and
* message digest. The message digest attribute value will be
* auto-calculated during signing and will be ignored if provided.
*
* Here's an example of providing these two attributes:
*
* forge.pkcs7.createSignedData();
* p7.addSigner({
* issuer: cert.issuer.attributes,
* serialNumber: cert.serialNumber,
* key: privateKey,
* digestAlgorithm: forge.pki.oids.sha1,
* authenticatedAttributes: [{
* type: forge.pki.oids.contentType,
* value: forge.pki.oids.data
* }, {
* type: forge.pki.oids.messageDigest
* }]
* });
*
* TODO: Support [subjectKeyIdentifier] as signer's ID.
*
* @param signer the signer information:
* key the signer's private key.
* [certificate] a certificate containing the public key
* associated with the signer's private key; use this option as
* an alternative to specifying signer.issuer and
* signer.serialNumber.
* [issuer] the issuer attributes (eg: cert.issuer.attributes).
* [serialNumber] the signer's certificate's serial number in
* hexadecimal (eg: cert.serialNumber).
* [digestAlgorithm] the message digest OID, as a string, to use
* (eg: forge.pki.oids.sha1).
* [authenticatedAttributes] an optional array of attributes
* to also sign along with the content.
*/
addSigner: function(signer) {
var issuer = signer.issuer;
var serialNumber = signer.serialNumber;
if(signer.certificate) {
var cert = signer.certificate;
if(typeof cert === 'string') {
cert = forge.pki.certificateFromPem(cert);
}
issuer = cert.issuer.attributes;
serialNumber = cert.serialNumber;
}
var key = signer.key;
if(!key) {
throw new Error(
'Could not add PKCS#7 signer; no private key specified.');
}
if(typeof key === 'string') {
key = forge.pki.privateKeyFromPem(key);
}
// ensure OID known for digest algorithm
var digestAlgorithm = signer.digestAlgorithm || forge.pki.oids.sha1;
switch(digestAlgorithm) {
case forge.pki.oids.sha1:
case forge.pki.oids.sha256:
case forge.pki.oids.sha384:
case forge.pki.oids.sha512:
case forge.pki.oids.md5:
break;
default:
throw new Error(
'Could not add PKCS#7 signer; unknown message digest algorithm: ' +
digestAlgorithm);
}
// if authenticatedAttributes is present, then the attributes
// must contain at least PKCS #9 content-type and message-digest
var authenticatedAttributes = signer.authenticatedAttributes || [];
if(authenticatedAttributes.length > 0) {
var contentType = false;
var messageDigest = false;
for(var i = 0; i < authenticatedAttributes.length; ++i) {
var attr = authenticatedAttributes[i];
if(!contentType && attr.type === forge.pki.oids.contentType) {
contentType = true;
if(messageDigest) {
break;
}
continue;
}
if(!messageDigest && attr.type === forge.pki.oids.messageDigest) {
messageDigest = true;
if(contentType) {
break;
}
continue;
}
}
if(!contentType || !messageDigest) {
throw new Error('Invalid signer.authenticatedAttributes. If ' +
'signer.authenticatedAttributes is specified, then it must ' +
'contain at least two attributes, PKCS #9 content-type and ' +
'PKCS #9 message-digest.');
}
}
msg.signers.push({
key: key,
version: 1,
issuer: issuer,
serialNumber: serialNumber,
digestAlgorithm: digestAlgorithm,
signatureAlgorithm: forge.pki.oids.rsaEncryption,
signature: null,
authenticatedAttributes: authenticatedAttributes,
unauthenticatedAttributes: []
});
},
/**
* Signs the content.
* @param options Options to apply when signing:
* [detached] boolean. If signing should be done in detached mode. Defaults to false.
*/
sign: function(options) {
options = options || {};
// auto-generate content info
if(typeof msg.content !== 'object' || msg.contentInfo === null) {
// use Data ContentInfo
msg.contentInfo = asn1.create(
asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// ContentType
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OID, false,
asn1.oidToDer(forge.pki.oids.data).getBytes())
]);
// add actual content, if present
if('content' in msg) {
var content;
if(msg.content instanceof forge.util.ByteBuffer) {
content = msg.content.bytes();
} else if(typeof msg.content === 'string') {
content = forge.util.encodeUtf8(msg.content);
}
if (options.detached) {
msg.detachedContent = asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OCTETSTRING, false, content);
} else {
msg.contentInfo.value.push(
// [0] EXPLICIT content
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 0, true, [
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OCTETSTRING, false,
content)
]));
}
}
}
// no signers, return early (degenerate case for certificate container)
if(msg.signers.length === 0) {
return;
}
// generate digest algorithm identifiers
var mds = addDigestAlgorithmIds();
// generate signerInfos
addSignerInfos(mds);
},
verify: function(caStore, options) {
if(!caStore) {
throw new Error('You must provide a CA store for PKCS#7 verification.');
}
var mds = addDigestAlgorithmIds();
return verifySignerInfos(mds, caStore, options || {});
},
/**
* Add a certificate.
*
* @param cert the certificate to add.
*/
addCertificate: function(cert) {
// convert from PEM
if(typeof cert === 'string') {
cert = forge.pki.certificateFromPem(cert);
}
msg.certificates.push(cert);
},
/**
* Add a certificate revokation list.
*
* @param crl the certificate revokation list to add.
*/
addCertificateRevokationList: function(crl) {
throw new Error('PKCS#7 CRL support not yet implemented.');
}
};
return msg;
function addDigestAlgorithmIds() {
var mds = {};
for(var i = 0; i < msg.signers.length; ++i) {
var signer = msg.signers[i];
var oid = signer.digestAlgorithm;
if(!(oid in mds)) {
// content digest
mds[oid] = forge.md[forge.pki.oids[oid]].create();
}
if(signer.authenticatedAttributes.length === 0) {
// no custom attributes to digest; use content message digest
signer.md = mds[oid];
} else {
// custom attributes to be digested; use own message digest
// TODO: optimize to just copy message digest state if that
// feature is ever supported with message digests
signer.md = forge.md[forge.pki.oids[oid]].create();
}
}
// add unique digest algorithm identifiers
msg.digestAlgorithmIdentifiers = [];
for(var oid in mds) {
msg.digestAlgorithmIdentifiers.push(
// AlgorithmIdentifier
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// algorithm
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OID, false,
asn1.oidToDer(oid).getBytes()),
// parameters (null)
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.NULL, false, '')
]));
}
return mds;
}
function addSignerInfos(mds) {
var content;
if (msg.detachedContent) {
// Signature has been made in detached mode.
content = msg.detachedContent;
} else {
// Note: ContentInfo is a SEQUENCE with 2 values, second value is
// the content field and is optional for a ContentInfo but required here
// since signers are present
// get ContentInfo content
content = msg.contentInfo.value[1];
// skip [0] EXPLICIT content wrapper
content = content.value[0];
}
if(!content) {
throw new Error(
'Could not sign PKCS#7 message; there is no content to sign.');
}
// get ContentInfo content type
var contentType = asn1.derToOid(msg.contentInfo.value[0].value);
// serialize content
var bytes = asn1.toDer(content);
// skip identifier and length per RFC 2315 9.3
// skip identifier (1 byte)
bytes.getByte();
// read and discard length bytes
asn1.getBerValueLength(bytes);
bytes = bytes.getBytes();
// digest content DER value bytes
for(var oid in mds) {
mds[oid].start().update(bytes);
}
// sign content
var signingTime = new Date();
for(var i = 0; i < msg.signers.length; ++i) {
var signer = msg.signers[i];
if(signer.authenticatedAttributes.length === 0) {
// if ContentInfo content type is not "Data", then
// authenticatedAttributes must be present per RFC 2315
if(contentType !== forge.pki.oids.data) {
throw new Error(
'Invalid signer; authenticatedAttributes must be present ' +
'when the ContentInfo content type is not PKCS#7 Data.');
}
} else {
// process authenticated attributes
// [0] IMPLICIT
signer.authenticatedAttributesAsn1 = asn1.create(
asn1.Class.CONTEXT_SPECIFIC, 0, true, []);
// per RFC 2315, attributes are to be digested using a SET container
// not the above [0] IMPLICIT container
var attrsAsn1 = asn1.create(
asn1.Class.UNIVERSAL, asn1.Type.SET, true, []);
for(var ai = 0; ai < signer.authenticatedAttributes.length; ++ai) {
var attr = signer.authenticatedAttributes[ai];
if(attr.type === forge.pki.oids.messageDigest) {
// use content message digest as value
attr.value = mds[signer.digestAlgorithm].digest();
} else if(attr.type === forge.pki.oids.signingTime) {
// auto-populate signing time if not already set
if(!attr.value) {
attr.value = signingTime;
}
}
// convert to ASN.1 and push onto Attributes SET (for signing) and
// onto authenticatedAttributesAsn1 to complete SignedData ASN.1
// TODO: optimize away duplication
attrsAsn1.value.push(_attributeToAsn1(attr));
signer.authenticatedAttributesAsn1.value.push(_attributeToAsn1(attr));
}
// DER-serialize and digest SET OF attributes only
bytes = asn1.toDer(attrsAsn1).getBytes();
signer.md.start().update(bytes);
}
// sign digest
signer.signature = signer.key.sign(signer.md, 'RSASSA-PKCS1-V1_5');
}
// add signer info
msg.signerInfos = _signersToAsn1(msg.signers);
}
function verifySignerInfos(mds, caStore, options) {
var content;
var rval = true;
if(msg.contentInfo !== null && msg.contentInfo.value[1]) {
// Note: ContentInfo is a SEQUENCE with 2 values, second value is
// the content field and is optional for a ContentInfo but required here
// since signers are present
// get ContentInfo content
content = msg.contentInfo.value[1];
// skip [0] EXPLICIT content wrapper
content = content.value[0];
} else if('content' in msg) {
// signature was likely made in detached mode
// caller must set p7.content before attempting to verify
if(msg.content instanceof forge.util.ByteBuffer) {
content = msg.content.bytes();
} else if(typeof msg.content === 'string') {
content = forge.util.encodeUtf8(msg.content);
}
content = asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OCTETSTRING, false, content);
}
if(!content) {
throw new Error(
'Could not verify PKCS#7 message; there is no content to verify.');
}
if(msg.signers.length === 0) {
throw new Error('There are no signatures to verify.');
}
// get ContentInfo content type
var contentType = asn1.derToOid(msg.contentInfo.value[0].value);
// serialize content
var bytes = asn1.toDer(content);
// skip identifier and length per RFC 2315 9.3
// skip identifier (1 byte)
bytes.getByte();
// read and discard length bytes
asn1.getBerValueLength(bytes);
bytes = bytes.getBytes();
// digest content DER value bytes
for(var oid in mds) {
mds[oid].start().update(bytes);
}
// verify content
for(var i = 0; i < msg.signers.length; ++i) {
var signer = msg.signers[i];
// find certificate
var signerCert = null;
for(var j = 0; j < msg.certificates.length; ++j) {
var cert = msg.certificates[j];
if(forge.util.compareDN({attributes: signer.issuer}, cert.issuer) &&
signer.serialNumber === cert.serialNumber) {
signerCert = cert;
}
}
if(signerCert === null) {
throw new Error('Unable to find signing certificate.');
}
var verifyOpts = {};
if(options.validityCheckDate) {
verifyOpts.validityCheckDate = options.validityCheckDate;
}
if(signer.authenticatedAttributes.length === 0) {
// if ContentInfo content type is not "Data", then
// authenticatedAttributes must be present per RFC 2315
if(contentType !== forge.pki.oids.data) {
throw new Error(
'Invalid signer; authenticatedAttributes must be present ' +
'when the ContentInfo content type is not PKCS#7 Data.');
}
} else {
// per RFC 2315, attributes are to be digested using a SET container
// not the above [0] IMPLICIT container
var attrsAsn1 = asn1.create(
asn1.Class.UNIVERSAL, asn1.Type.SET, true, []);
// if you have authenticated attributes, one of them must be the digest as this is how the content is verified
var foundDigest = false;
for(var ai in signer.authenticatedAttributes) {
switch(signer.authenticatedAttributes[ai].type) {
case forge.pki.oids.signingTime:
if(!verifyOpts.validityCheckDate) {
verifyOpts.validityCheckDate = signer.authenticatedAttributes[ai].value;
}
break;
case forge.pki.oids.messageDigest:
foundDigest = true;
signer.authenticatedAttributes[ai].value = mds[signer.digestAlgorithm].digest();
break;
default:
break;
}
attrsAsn1.value.push(_attributeToAsn1(signer.authenticatedAttributes[ai]));
}
if(!foundDigest) {
throw new Error('Authenticated attributes missing digest! Unable to verify signature.');
}
// DER-serialize and digest SET OF attributes only
bytes = asn1.toDer(attrsAsn1).getBytes();
signer.md.start().update(bytes);
}
forge.pki.verifyCertificateChain(caStore, msg.certificates, verifyOpts);
// verify digest
var verified = signerCert.publicKey.verify(signer.md.digest().bytes(), signer.signature, 'RSASSA-PKCS1-V1_5');
rval = rval && verified;
}
return rval;
}
};
/**
* Creates an empty PKCS#7 message of type EncryptedData.
*
* @return the message.
*/
p7.createEncryptedData = function() {
var msg = null;
msg = {
type: forge.pki.oids.encryptedData,
version: 0,
encryptedContent: {
algorithm: forge.pki.oids['aes256-CBC']
},
/**
* Reads an EncryptedData content block (in ASN.1 format)
*
* @param obj The ASN.1 representation of the EncryptedData content block
*/
fromAsn1: function(obj) {
// Validate EncryptedData content block and capture data.
_fromAsn1(msg, obj, p7.asn1.encryptedDataValidator);
},
/**
* Decrypt encrypted content
*
* @param key The (symmetric) key as a byte buffer
*/
decrypt: function(key) {
if(key !== undefined) {
msg.encryptedContent.key = key;
}
_decryptContent(msg);
}
};
return msg;
};
/**
* Creates an empty PKCS#7 message of type EnvelopedData.
*
* @return the message.
*/
p7.createEnvelopedData = function() {
var msg = null;
msg = {
type: forge.pki.oids.envelopedData,
version: 0,
recipients: [],
encryptedContent: {
algorithm: forge.pki.oids['aes256-CBC']
},
/**
* Reads an EnvelopedData content block (in ASN.1 format)
*
* @param obj the ASN.1 representation of the EnvelopedData content block.
*/
fromAsn1: function(obj) {
// validate EnvelopedData content block and capture data
var capture = _fromAsn1(msg, obj, p7.asn1.envelopedDataValidator);
msg.recipients = _recipientsFromAsn1(capture.recipientInfos.value);
},
toAsn1: function() {
// ContentInfo
return asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// ContentType
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OID, false,
asn1.oidToDer(msg.type).getBytes()),
// [0] EnvelopedData
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 0, true, [
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// Version
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.INTEGER, false,
asn1.integerToDer(msg.version).getBytes()),
// RecipientInfos
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SET, true,
_recipientsToAsn1(msg.recipients)),
// EncryptedContentInfo
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true,
_encryptedContentToAsn1(msg.encryptedContent))
])
])
]);
},
/**
* Find recipient by X.509 certificate's issuer.
*
* @param cert the certificate with the issuer to look for.
*
* @return the recipient object.
*/
findRecipient: function(cert) {
var sAttr = cert.issuer.attributes;
for(var i = 0; i < msg.recipients.length; ++i) {
var r = msg.recipients[i];
var rAttr = r.issuer;
if(r.serialNumber !== cert.serialNumber) {
continue;
}
if(rAttr.length !== sAttr.length) {
continue;
}
var match = true;
for(var j = 0; j < sAttr.length; ++j) {
if(rAttr[j].type !== sAttr[j].type ||
rAttr[j].value !== sAttr[j].value) {
match = false;
break;
}
}
if(match) {
return r;
}
}
return null;
},
/**
* Decrypt enveloped content
*
* @param recipient The recipient object related to the private key
* @param privKey The (RSA) private key object
*/
decrypt: function(recipient, privKey) {
if(msg.encryptedContent.key === undefined && recipient !== undefined &&
privKey !== undefined) {
switch(recipient.encryptedContent.algorithm) {
case forge.pki.oids.rsaEncryption:
case forge.pki.oids.desCBC:
var key = privKey.decrypt(recipient.encryptedContent.content);
msg.encryptedContent.key = forge.util.createBuffer(key);
break;
default:
throw new Error('Unsupported asymmetric cipher, ' +
'OID ' + recipient.encryptedContent.algorithm);
}
}
_decryptContent(msg);
},
/**
* Add (another) entity to list of recipients.
*
* @param cert The certificate of the entity to add.
*/
addRecipient: function(cert) {
msg.recipients.push({
version: 0,
issuer: cert.issuer.attributes,
serialNumber: cert.serialNumber,
encryptedContent: {
// We simply assume rsaEncryption here, since forge.pki only
// supports RSA so far. If the PKI module supports other
// ciphers one day, we need to modify this one as well.
algorithm: forge.pki.oids.rsaEncryption,
key: cert.publicKey
}
});
},
/**
* Encrypt enveloped content.
*
* This function supports two optional arguments, cipher and key, which
* can be used to influence symmetric encryption. Unless cipher is
* provided, the cipher specified in encryptedContent.algorithm is used
* (defaults to AES-256-CBC). If no key is provided, encryptedContent.key
* is (re-)used. If that one's not set, a random key will be generated
* automatically.
*
* @param [key] The key to be used for symmetric encryption.
* @param [cipher] The OID of the symmetric cipher to use.
*/
encrypt: function(key, cipher) {
// Part 1: Symmetric encryption
if(msg.encryptedContent.content === undefined) {
cipher = cipher || msg.encryptedContent.algorithm;
key = key || msg.encryptedContent.key;
var keyLen, ivLen, ciphFn;
switch(cipher) {
case forge.pki.oids['aes128-CBC']:
keyLen = 16;
ivLen = 16;
ciphFn = forge.aes.createEncryptionCipher;
break;
case forge.pki.oids['aes192-CBC']:
keyLen = 24;
ivLen = 16;
ciphFn = forge.aes.createEncryptionCipher;
break;
case forge.pki.oids['aes256-CBC']:
keyLen = 32;
ivLen = 16;
ciphFn = forge.aes.createEncryptionCipher;
break;
case forge.pki.oids['des-EDE3-CBC']:
keyLen = 24;
ivLen = 8;
ciphFn = forge.des.createEncryptionCipher;
break;
default:
throw new Error('Unsupported symmetric cipher, OID ' + cipher);
}
if(key === undefined) {
key = forge.util.createBuffer(forge.random.getBytes(keyLen));
} else if(key.length() != keyLen) {
throw new Error('Symmetric key has wrong length; ' +
'got ' + key.length() + ' bytes, expected ' + keyLen + '.');
}
// Keep a copy of the key & IV in the object, so the caller can
// use it for whatever reason.
msg.encryptedContent.algorithm = cipher;
msg.encryptedContent.key = key;
msg.encryptedContent.parameter = forge.util.createBuffer(
forge.random.getBytes(ivLen));
var ciph = ciphFn(key);
ciph.start(msg.encryptedContent.parameter.copy());
ciph.update(msg.content);
// The finish function does PKCS#7 padding by default, therefore
// no action required by us.
if(!ciph.finish()) {
throw new Error('Symmetric encryption failed.');
}
msg.encryptedContent.content = ciph.output;
}
// Part 2: asymmetric encryption for each recipient
for(var i = 0; i < msg.recipients.length; ++i) {
var recipient = msg.recipients[i];
// Nothing to do, encryption already done.
if(recipient.encryptedContent.content !== undefined) {
continue;
}
switch(recipient.encryptedContent.algorithm) {
case forge.pki.oids.rsaEncryption:
recipient.encryptedContent.content =
recipient.encryptedContent.key.encrypt(
msg.encryptedContent.key.data);
break;
default:
throw new Error('Unsupported asymmetric cipher, OID ' +
recipient.encryptedContent.algorithm);
}
}
}
};
return msg;
};
/**
* Converts a single recipient from an ASN.1 object.
*
* @param obj the ASN.1 RecipientInfo.
*
* @return the recipient object.
*/
function _recipientFromAsn1(obj) {
// validate EnvelopedData content block and capture data
var capture = {};
var errors = [];
if(!asn1.validate(obj, p7.asn1.recipientInfoValidator, capture, errors)) {
var error = new Error('Cannot read PKCS#7 RecipientInfo. ' +
'ASN.1 object is not an PKCS#7 RecipientInfo.');
error.errors = errors;
throw error;
}
return {
version: capture.version.charCodeAt(0),
issuer: forge.pki.RDNAttributesAsArray(capture.issuer),
serialNumber: forge.util.createBuffer(capture.serial).toHex(),
encryptedContent: {
algorithm: asn1.derToOid(capture.encAlgorithm),
parameter: capture.encParameter.value,
content: capture.encKey
}
};
}
/**
* Converts a single recipient object to an ASN.1 object.
*
* @param obj the recipient object.
*
* @return the ASN.1 RecipientInfo.
*/
function _recipientToAsn1(obj) {
return asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// Version
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.INTEGER, false,
asn1.integerToDer(obj.version).getBytes()),
// IssuerAndSerialNumber
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// Name
forge.pki.distinguishedNameToAsn1({attributes: obj.issuer}),
// Serial
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.INTEGER, false,
forge.util.hexToBytes(obj.serialNumber))
]),
// KeyEncryptionAlgorithmIdentifier