int getPgpPacketInfo( INOUT STREAM *stream,
OUT QUERY_INFO *queryInfo )
{
const long startPos = stell( stream );
long offset, length;
int ctb, status;
assert( isWritePtr( stream, sizeof( STREAM ) ) );
assert( isWritePtr( queryInfo, sizeof( QUERY_INFO ) ) );
/* Clear return value */
memset( queryInfo, 0, sizeof( QUERY_INFO ) );
/* Read the packet header and extract information from the CTB. Note
that the assignment of version numbers is speculative only because
it's possible to use PGP 2.x packet headers to wrap up OpenPGP
packets */
status = pgpReadPacketHeader( stream, &ctb, &length, 8 );
if( cryptStatusError( status ) )
return( status );
queryInfo->formatType = CRYPT_FORMAT_PGP;
queryInfo->version = pgpGetPacketVersion( ctb );
offset = stell( stream );
if( cryptStatusError( offset ) )
return( offset );
queryInfo->size = ( offset - startPos ) + length;
switch( pgpGetPacketType( ctb ) )
{
case PGP_PACKET_SKE:
queryInfo->type = CRYPT_OBJECT_ENCRYPTED_KEY;
break;
case PGP_PACKET_PKE:
queryInfo->type = CRYPT_OBJECT_PKCENCRYPTED_KEY;
break;
case PGP_PACKET_SIGNATURE:
queryInfo->type = CRYPT_OBJECT_SIGNATURE;
break;
case PGP_PACKET_SIGNATURE_ONEPASS:
/* First half of a one-pass signature, this is given a special
type of 'none' since it's not a normal packet */
queryInfo->type = CRYPT_OBJECT_NONE;
break;
default:
DEBUG_DIAG(( "Found unrecognised ctb %X", ctb ));
assert( DEBUG_WARN );
return( CRYPT_ERROR_BADDATA );
}
/* Make sure that all of the data is present without resetting the
stream */
return( ( sMemDataLeft( stream ) < length ) ? \
CRYPT_ERROR_UNDERFLOW : CRYPT_OK );
}
static int readKey( INOUT STREAM *stream,
INOUT PGP_INFO *pgpInfo,
IN_INT_SHORT_Z const int keyGroupNo,
INOUT ERROR_INFO *errorInfo )
{
PGP_KEYINFO *keyInfo = &pgpInfo->key;
HASHFUNCTION hashFunction;
HASHINFO hashInfo;
BYTE hash[ CRYPT_MAX_HASHSIZE + 8 ], packetHeader[ 64 + 8 ];
BOOLEAN isPublicKey = TRUE, isPrimaryKey = FALSE;
void *pubKeyPayload;
long packetLength;
int pubKeyPos, pubKeyPayloadPos, endPos, pubKeyPayloadLen;
int ctb, length, value, hashSize, iterationCount, status;
assert( isWritePtr( stream, sizeof( STREAM ) ) );
assert( isWritePtr( pgpInfo, sizeof( PGP_INFO ) ) );
REQUIRES( keyGroupNo >= 0 && keyGroupNo < MAX_INTLENGTH_SHORT );
REQUIRES( errorInfo != NULL );
/* Process the CTB and packet length */
ctb = sPeek( stream );
if( cryptStatusError( ctb ) )
{
/* If there was an error reading the CTB, which is the first byte of
the packet group, it means that we've run out of data so we
return the status as a not-found error rather than the actual
stream status */
return( CRYPT_ERROR_NOTFOUND );
}
switch( pgpGetPacketType( ctb ) )
{
case PGP_PACKET_SECKEY_SUB:
keyInfo = &pgpInfo->subKey;
isPublicKey = FALSE;
break;
case PGP_PACKET_SECKEY:
isPublicKey = FALSE;
break;
case PGP_PACKET_PUBKEY_SUB:
keyInfo = &pgpInfo->subKey;
break;
case PGP_PACKET_PUBKEY:
isPrimaryKey = TRUE;
break;
default:
retExt( CRYPT_ERROR_BADDATA,
( CRYPT_ERROR_BADDATA, errorInfo,
"Invalid PGP CTB %02X for key packet group %d",
ctb, keyGroupNo ) );
}
status = pgpReadPacketHeader( stream, NULL, &packetLength, 64 );
if( cryptStatusError( status ) )
{
retExt( status,
( status, errorInfo,
"Invalid PGP key packet header for key packet group %d",
keyGroupNo ) );
}
if( packetLength < 64 || packetLength > sMemDataLeft( stream ) )
{
retExt( CRYPT_ERROR_BADDATA,
( CRYPT_ERROR_BADDATA, errorInfo,
"Invalid PGP key packet length %ld for key packet group %d",
packetLength, keyGroupNo ) );
}
/* Since there can (in theory) be arbitrary numbers of subkeys and other
odds and ends attached to a key and the details of what to do with
these things gets a bit vague, we just skip any further subkeys that
may be present */
if( keyInfo->pkcAlgo != CRYPT_ALGO_NONE )
{
status = sSkip( stream, packetLength );
for( iterationCount = 0;
cryptStatusOK( status ) && \
iterationCount < FAILSAFE_ITERATIONS_MED;
iterationCount++ )
{
status = readUserID( stream, pgpInfo,
isPrimaryKey ? &hashInfo : NULL );
}
ENSURES( iterationCount < FAILSAFE_ITERATIONS_MED );
if( cryptStatusError( status ) && status != OK_SPECIAL )
{
retExt( status,
( status, errorInfo,
"Invalid additional PGP subkey information for key "
"packet group %d", keyGroupNo ) );
}
/* We've skipped the current subkey, we're done */
return( CRYPT_OK );
}
/* Determine which bits make up the public and the private key data. The
public-key data starts at the version number and includes the date,
validity, and public-key components. Since there's no length
information included for this data block we have to record bookmarks
and then later retroactively calculate the length based on how much
data we've read in the meantime:
pubKey pubKeyPayload privKey endPos
| | | |
v v v v
+---+---------------------------+-------------------+
|hdr| | Public key | Private key |
+---+---------------------------+-------------------+
| |<pubKeyPayloadLen->| |
|<----- pubKeyDataLen ----->|<-- privKeyDLen -->|
|<--------------- packetLength ---------------->| */
pubKeyPos = stell( stream );
endPos = pubKeyPos + packetLength;
ENSURES( endPos > pubKeyPos && endPos < MAX_BUFFER_SIZE );
status = value = sgetc( stream );
if( cryptStatusError( status ) )
return( status );
if( value != PGP_VERSION_2 && value != PGP_VERSION_3 && \
value != PGP_VERSION_OPENPGP )
{
/* Unknown version number, skip this packet */
return( OK_SPECIAL );
}
pgpInfo->isOpenPGP = ( value == PGP_VERSION_OPENPGP ) ? TRUE : FALSE;
/* Build the packet header, which is hashed along with the key components
to get the OpenPGP keyID. This is generated anyway when the context
is created but we need to generate it here as well in order to locate
the key in the first place:
byte ctb = 0x99
byte[2] length
byte version = 4
byte[4] key generation time
[ byte[2] validity time - PGP 2.x only ]
byte[] key data
We can't add the length or key data yet since we have to parse the
key data to know how long it is, so we can only build the static part
of the header at this point */
packetHeader[ 0 ] = 0x99;
packetHeader[ 3 ] = PGP_VERSION_OPENPGP;
/* Read the timestamp and validity period (for PGP 2.x keys) */
status = sread( stream, packetHeader + 4, 4 );
if( !cryptStatusError( status ) && !pgpInfo->isOpenPGP )
status = sSkip( stream, 2 );
if( cryptStatusError( status ) )
return( status );
/* Read the public key components */
pubKeyPayloadPos = stell( stream );
status = readPublicKeyComponents( stream, keyInfo, &length );
if( cryptStatusError( status ) )
{
/* If the error status is OK_SPECIAL then the problem was an
unrecognised algorithm or something similar so we just skip the
packet */
if( status == OK_SPECIAL )
{
DEBUG_DIAG(( "Encountered unrecognised algorithm while "
"reading key" ));
assert( DEBUG_WARN );
return( OK_SPECIAL );
}
retExt( status,
( status, errorInfo,
"Invalid PGP public-key components for key packet group %d",
keyGroupNo ) );
}
/* Now that we know where the public key data starts and finishes, we
can set up references to it */
keyInfo->pubKeyDataLen = stell( stream ) - pubKeyPos;
status = sMemGetDataBlockAbs( stream, pubKeyPos, &keyInfo->pubKeyData,
keyInfo->pubKeyDataLen );
if( cryptStatusError( status ) )
{
DEBUG_DIAG(( "Couldn't set up reference to key data" ));
assert( DEBUG_WARN );
return( status );
}
pubKeyPayloadLen = stell( stream ) - pubKeyPayloadPos;
status = sMemGetDataBlockAbs( stream, pubKeyPayloadPos, &pubKeyPayload,
pubKeyPayloadLen );
if( cryptStatusError( status ) )
{
DEBUG_DIAG(( "Couldn't set up reference to key data" ));
assert( DEBUG_WARN );
return( status );
}
/* Complete the packet header that we read earlier on by adding the
length information */
packetHeader[ 1 ] = intToByte( ( ( 1 + 4 + length ) >> 8 ) & 0xFF );
packetHeader[ 2 ] = intToByte( ( 1 + 4 + length ) & 0xFF );
/* Hash the data needed to generate the OpenPGP keyID */
getHashParameters( CRYPT_ALGO_SHA1, 0, &hashFunction, &hashSize );
hashFunction( hashInfo, NULL, 0, packetHeader, 1 + 2 + 1 + 4,
HASH_STATE_START );
hashFunction( hashInfo, hash, CRYPT_MAX_HASHSIZE,
pubKeyPayload, pubKeyPayloadLen, HASH_STATE_END );
memcpy( keyInfo->openPGPkeyID, hash + hashSize - PGP_KEYID_SIZE,
PGP_KEYID_SIZE );
/* If it's a private keyring, process the private key components */
if( !isPublicKey )
{
/* Handle decryption information for private-key components if
necessary */
status = readPrivateKeyDecryptionInfo( stream, keyInfo );
if( cryptStatusError( status ) )
{
/* If the error status is OK_SPECIAL then the problem was an
unrecognised algorithm or something similar so we just skip
the packet */
if( status == OK_SPECIAL )
{
DEBUG_DIAG(( "Encountered unrecognised algorithm while "
"reading key" ));
assert( DEBUG_WARN );
return( OK_SPECIAL );
}
retExt( status,
( status, errorInfo,
"Invalid PGP private-key decryption information for "
"key packet group %d", keyGroupNo ) );
}
/* What's left is the private-key data */
keyInfo->privKeyDataLen = endPos - stell( stream );
status = sMemGetDataBlock( stream, &keyInfo->privKeyData,
keyInfo->privKeyDataLen );
if( cryptStatusOK( status ) )
status = sSkip( stream, keyInfo->privKeyDataLen );
if( cryptStatusError( status ) )
return( status );
}
/* If it's the primary key, start hashing it in preparation for
performing signature checks on subpackets */
if( isPrimaryKey )
{
packetHeader[ 0 ] = 0x99;
packetHeader[ 1 ] = intToByte( ( keyInfo->pubKeyDataLen >> 8 ) & 0xFF );
packetHeader[ 2 ] = intToByte( keyInfo->pubKeyDataLen & 0xFF );
hashFunction( hashInfo, NULL, 0, packetHeader, 1 + 2,
HASH_STATE_START );
hashFunction( hashInfo, NULL, 0, keyInfo->pubKeyData,
keyInfo->pubKeyDataLen, HASH_STATE_CONTINUE );
}
/* Read any associated subpacket(s), of which the only ones of real
interest are the userID packet(s) */
for( iterationCount = 0;
cryptStatusOK( status ) && \
iterationCount < FAILSAFE_ITERATIONS_MED;
iterationCount++ )
{
status = readUserID( stream, pgpInfo,
isPrimaryKey ? &hashInfo : NULL );
}
ENSURES( iterationCount < FAILSAFE_ITERATIONS_MED );
if( cryptStatusError( status ) && status != OK_SPECIAL )
{
retExt( status,
( status, errorInfo,
"Invalid PGP userID information for key packet group %d",
keyGroupNo ) );
}
/* If there's no user ID present, set a generic label */
if( pgpInfo->lastUserID <= 0 )
{
pgpInfo->userID[ 0 ] = "PGP key (no user ID found)";
pgpInfo->userIDlen[ 0 ] = 26;
pgpInfo->lastUserID = 1;
}
return( CRYPT_OK );
}
static int scanPacketGroup( INOUT STREAM *stream,
OUT_LENGTH_SHORT_Z int *packetGroupLength,
const BOOLEAN isLastGroup )
{
BOOLEAN firstPacket = TRUE, skipPackets = FALSE;
int endPos = 0, iterationCount, status = CRYPT_OK;
assert( isReadPtr( stream, sizeof( STREAM ) ) );
assert( isWritePtr( packetGroupLength, sizeof( int ) ) );
/* Clear return value */
*packetGroupLength = 0;
for( iterationCount = 0; iterationCount < FAILSAFE_ITERATIONS_LARGE;
iterationCount++ )
{
long length;
int ctb, type;
/* Get the next CTB. If it's the start of another packet group,
we're done */
ctb = status = sPeek( stream );
if( cryptStatusOK( status ) && !( pgpIsCTB( ctb ) ) )
status = CRYPT_ERROR_BADDATA;
if( cryptStatusError( status ) )
{
/* If we ran out of input data let the caller know, however if
this is the last packet group then running out of data isn't
an error */
if( status == CRYPT_ERROR_UNDERFLOW )
{
if( !isLastGroup )
skipPackets = TRUE;
break;
}
return( status );
}
type = pgpGetPacketType( ctb );
if( firstPacket )
{
/* If the packet group doesn't start with the expected packet
type, skip packets to try and resync */
if( type != PGP_PACKET_PUBKEY && type != PGP_PACKET_SECKEY )
skipPackets = TRUE;
firstPacket = FALSE;
}
else
{
/* If we've found the start of a new packet group, we're done */
if( type == PGP_PACKET_PUBKEY || type == PGP_PACKET_SECKEY )
break;
}
/* Skip the current packet in the buffer */
status = pgpReadPacketHeader( stream, NULL, &length, \
getMinPacketSize( type ) );
if( cryptStatusOK( status ) )
{
endPos = stell( stream ) + length;
status = sSkip( stream, length );
}
if( cryptStatusError( status ) )
{
/* If we ran out of input data let the caller know */
if( status == CRYPT_ERROR_UNDERFLOW )
{
skipPackets = TRUE;
break;
}
return( status );
}
}
ENSURES( iterationCount < FAILSAFE_ITERATIONS_LARGE );
/* Remember where the current packet group ends. If we skipped packets
or consumed all of the input in the buffer and there's more present
beyond that, tell the caller to discard the data and try again */
*packetGroupLength = endPos;
return( skipPackets ? OK_SPECIAL : CRYPT_OK );
}
static int readUserID( INOUT STREAM *stream,
INOUT_OPT PGP_INFO *pgpInfo,
INOUT_OPT HASHINFO *hashInfo )
{
HASHINFO localHashInfo;
long packetLength;
int ctb, packetType = DUMMY_INIT, iterationCount, status;
assert( isWritePtr( stream, sizeof( STREAM ) ) );
assert( pgpInfo == NULL || \
isWritePtr( pgpInfo, sizeof( PGP_INFO ) ) );
assert( hashInfo == NULL || \
isWritePtr( hashInfo, sizeof( HASHINFO ) ) );
/* Take a local copy of the hash information from the primary key
packet */
if( hashInfo != NULL )
memcpy( &localHashInfo, hashInfo, sizeof( HASHINFO ) );
/* Skip keyring trust packets, signature packets, and any private
packets (GPG uses packet type 61, which might be a DSA self-
signature).
PGP has two ways of indicating key usage, either directly via the key
type (e.g. PGP_ALGO_RSA_ENCRYPT vs. PGP_ALGO_RSA_SIGN) or in a rather
schizophrenic manner in signature packets by allowing the signer to
specify an X.509-style key usage. Since it can appear in both self-
sigs and certification signatures, the exact usage for a key is
somewhat complex to determine as a certification signer could
indicate that they trust the key when it's used for signing while a
self-signer could indicate that the key should be used for
encryption. This appears to be a preference indication rather than a
hard limit like the X.509 keyUsage and also contains other odds and
ends as well such as key splitting indicators. For now we don't make
use of these flags as it's a bit difficult to figure out what's what,
and in any case DSA vs. Elgamal doesn't need any further constraints
since there's only one usage possible */
for( status = CRYPT_OK, iterationCount = 0;
cryptStatusOK( status ) && iterationCount < FAILSAFE_ITERATIONS_MED;
iterationCount++ )
{
/* See what we've got. If we've run out of input or it's a non-key-
related packet, we're done */
status = ctb = sPeek( stream );
if( cryptStatusError( status ) )
break;
packetType = pgpGetPacketType( ctb );
if( packetType != PGP_PACKET_TRUST && \
packetType != PGP_PACKET_SIGNATURE && \
packetType != PGP_PACKET_USERATTR && \
!pgpIsReservedPacket( packetType ) )
break;
/* Skip the packet. If we get an error at this point we don't
immediately bail out but try and return at least a partial
response */
status = pgpReadPacketHeader( stream, &ctb, &packetLength, \
getMinPacketSize( packetType ) );
if( cryptStatusError( status ) )
break;
status = sSkip( stream, packetLength );
}
ENSURES( iterationCount < FAILSAFE_ITERATIONS_MED );
/* If we've reached the end of the current collection of key packets,
let the caller know that we're done. Note that running out of input
is a valid condition so we don't return a fatal error code at this
point */
if( cryptStatusError( status ) || packetType != PGP_PACKET_USERID )
return( OK_SPECIAL );
/* Record the userID (unless we're skipping the packet). If there are
more userIDs than we can record we silently ignore them. This
handles keys with weird numbers of userIDs without rejecting them
just because they have, well, a weird number of userIDs */
status = pgpReadPacketHeader( stream, &ctb, &packetLength, \
getMinPacketSize( packetType ) );
if( cryptStatusError( status ) )
return( status );
if( pgpInfo != NULL && pgpInfo->lastUserID < MAX_PGP_USERIDS )
{
void *dataPtr;
status = sMemGetDataBlock( stream, &dataPtr, packetLength );
if( cryptStatusError( status ) )
return( status );
pgpInfo->userID[ pgpInfo->lastUserID ] = dataPtr;
pgpInfo->userIDlen[ pgpInfo->lastUserID++ ] = ( int ) packetLength;
}
return( sSkip( stream, packetLength ) );
}
