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|
/**
* Javascript implementation of PKCS#7 v1.5. Currently only certain parts of
* PKCS#7 are implemented, especially the enveloped-data content type.
*
* @author Stefan Siegl
*
* Copyright (c) 2012 Stefan Siegl <stesie@brokenpipe.de>
*
* Currently this implementation only supports ContentType of either
* EnvelopedData or EncryptedData on 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 seperate file pkcs7asn1.js, since those are referenced from other
* PKCS standards like PKCS #12.
*/
(function() {
/* ########## Begin module implementation ########## */
function initModule(forge) {
// shortcut for ASN.1 API
var asn1 = forge.asn1;
// shortcut for PKCS#7 API
var p7 = 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;
};
/**
* Converts a single RecipientInfo from an ASN.1 object.
*
* @param obj The ASN.1 representation of a RecipientInfo.
*
* @return The recipientInfo object.
*/
var _recipientInfoFromAsn1 = function(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 message. ' +
'ASN.1 object is not an PKCS#7 EnvelopedData.');
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 recipientInfo object to an ASN.1 object.
*
* @param obj The recipientInfo object.
*
* @return The ASN.1 representation of a RecipientInfo.
*/
var _recipientInfoToAsn1 = function(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
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// Algorithm
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OID, false,
asn1.oidToDer(obj.encryptedContent.algorithm).getBytes()),
// Parameter, force NULL, only RSA supported for now.
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.NULL, false, '')
]),
// EncryptedKey
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OCTETSTRING, false,
obj.encryptedContent.content)
]);
};
/**
* Map a set of RecipientInfo ASN.1 objects to recipientInfo objects.
*
* @param objArr Array of ASN.1 representations RecipientInfo (i.e. SET OF).
*
* @return array of recipientInfo objects.
*/
var _recipientInfosFromAsn1 = function(objArr) {
var ret = [];
for(var i = 0; i < objArr.length; i ++) {
ret.push(_recipientInfoFromAsn1(objArr[i]));
}
return ret;
};
/**
* Map an array of recipientInfo objects to ASN.1 objects.
*
* @param recipientsArr Array of recipientInfo objects.
*
* @return Array of ASN.1 representations RecipientInfo.
*/
var _recipientInfosToAsn1 = function(recipientsArr) {
var ret = [];
for(var i = 0; i < recipientsArr.length; i ++) {
ret.push(_recipientInfoToAsn1(recipientsArr[i]));
}
return ret;
};
/**
* Map messages encrypted content to ASN.1 objects.
*
* @param ec The encryptedContent object of the message.
*
* @return ASN.1 representation of the encryptedContent object (SEQUENCE).
*/
var _encryptedContentToAsn1 = function(ec) {
return [
// ContentType, always Data for the moment
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OID, false,
asn1.oidToDer(forge.pki.oids.data).getBytes()),
// ContentEncryptionAlgorithmIdentifier
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SEQUENCE, true, [
// Algorithm
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OID, false,
asn1.oidToDer(ec.algorithm).getBytes()),
// Parameters (IV)
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OCTETSTRING, false,
ec.parameter.getBytes())
]),
// [0] EncryptedContent
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 0, true, [
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OCTETSTRING, false,
ec.content.getBytes())
])
];
};
/**
* Reads the "common part" of an PKCS#7 content block (in ASN.1 format)
*
* This function reads the "common part" of the PKCS#7 content blocks
* EncryptedData and EnvelopedData, i.e. version number and symmetrically
* encrypted content block.
*
* The result of the ASN.1 validate and capture process is returned
* to allow the caller to extract further data, e.g. the list of recipients
* in case of a EnvelopedData object.
*
* @param msg the PKCS#7 object to read the data to.
* @param obj the ASN.1 representation of the content block.
* @param validator the ASN.1 structure validator object to use.
*
* @return the value map captured by validator object.
*/
var _fromAsn1 = function(msg, obj, validator) {
var capture = {};
var errors = [];
if(!asn1.validate(obj, validator, capture, errors)) {
var error = new Error('Cannot read PKCS#7 message. ' +
'ASN.1 object is not a supported PKCS#7 message.');
error.errors = error;
throw error;
}
// Check contentType, so far we only support (raw) Data.
var contentType = asn1.derToOid(capture.contentType);
if(contentType !== forge.pki.oids.data) {
throw new Error('Unsupported PKCS#7 message. ' +
'Only wrapped ContentType Data supported.');
}
if(capture.encryptedContent) {
var content = '';
if(forge.util.isArray(capture.encryptedContent)) {
for(var i = 0; i < capture.encryptedContent.length; ++i) {
if(capture.encryptedContent[i].type !== asn1.Type.OCTETSTRING) {
throw new Error('Malformed PKCS#7 message, expecting encrypted ' +
'content constructed of only OCTET STRING objects.');
}
content += capture.encryptedContent[i].value;
}
} else {
content = capture.encryptedContent;
}
msg.encryptedContent = {
algorithm: asn1.derToOid(capture.encAlgorithm),
parameter: forge.util.createBuffer(capture.encParameter.value),
content: forge.util.createBuffer(content)
};
}
if(capture.content) {
var content = '';
if(forge.util.isArray(capture.content)) {
for(var i = 0; i < capture.content.length; ++i) {
if(capture.content[i].type !== asn1.Type.OCTETSTRING) {
throw new Error('Malformed PKCS#7 message, expecting ' +
'content constructed of only OCTET STRING objects.');
}
content += capture.content[i].value;
}
} else {
content = capture.content;
}
msg.content = forge.util.createBuffer(content);
}
msg.version = capture.version.charCodeAt(0);
msg.rawCapture = capture;
return capture;
};
/**
* Decrypt the symmetrically encrypted content block of the PKCS#7 message.
*
* Decryption is skipped in case the PKCS#7 message object already has a
* (decrypted) content attribute. The algorithm, key and cipher parameters
* (probably the iv) are taken from the encryptedContent attribute of the
* message object.
*
* @param The PKCS#7 message object.
*/
var _decryptContent = function (msg) {
if(msg.encryptedContent.key === undefined) {
throw new Error('Symmetric key not available.');
}
if(msg.content === undefined) {
var ciph;
switch(msg.encryptedContent.algorithm) {
case forge.pki.oids['aes128-CBC']:
case forge.pki.oids['aes192-CBC']:
case forge.pki.oids['aes256-CBC']:
ciph = forge.aes.createDecryptionCipher(msg.encryptedContent.key);
break;
case forge.pki.oids['desCBC']:
case forge.pki.oids['des-EDE3-CBC']:
ciph = forge.des.createDecryptionCipher(msg.encryptedContent.key);
break;
default:
throw new Error('Unsupported symmetric cipher, OID ' +
msg.encryptedContent.algorithm);
}
ciph.start(msg.encryptedContent.parameter);
ciph.update(msg.encryptedContent.content);
if(!ciph.finish()) {
throw new Error('Symmetric decryption failed.');
}
msg.content = ciph.output;
}
};
p7.createSignedData = function() {
var msg = null;
msg = {
type: forge.pki.oids.signedData,
version: 1,
certificates: [],
crls: [],
// 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 = [];
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
},
toAsn1: function() {
// TODO: add support for more data types here
if('content' in msg) {
throw new Error('Signing PKCS#7 content not yet implemented.');
}
// 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[0]));
}
var crls = [];
// TODO: implement CRLs
// 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
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,
// [0] IMPLICIT ExtendedCertificatesAndCertificates
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 0, true, certs),
// [1] IMPLICIT CertificateRevocationLists
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 1, true, crls),
// SignerInfos
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.SET, true,
msg.signerInfos)
])
])
]);
},
/**
* Signs the content.
*
* @param signer the signer (or array of signers) to sign as, for each:
* key the private key to sign with.
* [md] the message digest to use, defaults to sha-1.
*/
sign: function(signer) {
if('content' in msg) {
throw new Error('PKCS#7 signing not yet implemented.');
}
if(typeof msg.content !== 'object') {
// 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) {
msg.contentInfo.value.push(
// [0] EXPLICIT content
asn1.create(asn1.Class.CONTEXT_SPECIFIC, 0, true, [
asn1.create(asn1.Class.UNIVERSAL, asn1.Type.OCTETSTRING, false,
msg.content)
]));
}
}
// TODO: generate digest algorithm identifiers
// TODO: generate signerInfos
},
verify: function() {
throw new Error('PKCS#7 signature verification not yet implemented.');
},
/**
* 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;
};
/**
* 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 = _recipientInfosFromAsn1(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,
_recipientInfosToAsn1(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;
};
} // end module implementation
/* ########## Begin module wrapper ########## */
var name = 'pkcs7';
if(typeof define !== 'function') {
// NodeJS -> AMD
if(typeof module === 'object' && module.exports) {
var nodeJS = true;
define = function(ids, factory) {
factory(require, module);
};
} else {
// <script>
if(typeof forge === 'undefined') {
forge = {};
}
return initModule(forge);
}
}
// AMD
var deps;
var defineFunc = function(require, module) {
module.exports = function(forge) {
var mods = deps.map(function(dep) {
return require(dep);
}).concat(initModule);
// handle circular dependencies
forge = forge || {};
forge.defined = forge.defined || {};
if(forge.defined[name]) {
return forge[name];
}
forge.defined[name] = true;
for(var i = 0; i < mods.length; ++i) {
mods[i](forge);
}
return forge[name];
};
};
var tmpDefine = define;
define = function(ids, factory) {
deps = (typeof ids === 'string') ? factory.slice(2) : ids.slice(2);
if(nodeJS) {
delete define;
return tmpDefine.apply(null, Array.prototype.slice.call(arguments, 0));
}
define = tmpDefine;
return define.apply(null, Array.prototype.slice.call(arguments, 0));
};
define([
'require',
'module',
'./aes',
'./asn1',
'./des',
'./oids',
'./pem',
'./pkcs7asn1',
'./random',
'./util',
'./x509'
], function() {
defineFunc.apply(null, Array.prototype.slice.call(arguments, 0));
});
})();
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