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Diffstat (limited to 'contrib/file/magic/Magdir/pgp-binary-keys')
| -rw-r--r-- | contrib/file/magic/Magdir/pgp-binary-keys | 388 |
1 files changed, 388 insertions, 0 deletions
diff --git a/contrib/file/magic/Magdir/pgp-binary-keys b/contrib/file/magic/Magdir/pgp-binary-keys new file mode 100644 index 000000000000..1ce76d907b07 --- /dev/null +++ b/contrib/file/magic/Magdir/pgp-binary-keys @@ -0,0 +1,388 @@ + +#------------------------------------------------------------------------------ +# $File: pgp-binary-keys,v 1.2 2021/04/26 15:56:00 christos Exp $ +# pgp-binary-keys: This file handles pgp binary keys. +# +# An PGP certificate or message doesn't have a fixed header. Instead, +# they are sequences of packets: +# +# https://tools.ietf.org/html/rfc4880#section-4.3 +# +# whose order conforms to a grammar: +# +# https://tools.ietf.org/html/rfc4880#section-11 +# +# Happily most packets have a few fields that are constrained, which +# allow us to fingerprint them with relatively high certainty. +# +# A PGP packet is described by a single byte: the so-called CTB. The +# high-bit is always set. If bit 6 is set, then it is a so-called +# new-style CTB; if bit 6 is clear, then it is a so-called old-style +# CTB. Old-style CTBs have only four bits of type information; bits +# 1-0 are used to describe the length. New-style CTBs have 6 bits of +# type information. +# +# Following the CTB is the packet's length in bytes. If we blindly +# advance the file cursor by this amount past the end of the length +# information we come to the next packet. +# +# Data Structures +# =============== +# +# New Style CTB +# ------------- +# +# https://tools.ietf.org/html/rfc4880#section-4.2.2 +# +# 76543210 +# ||\----/ +# || tag +# |always 1 +# always 1 +# +# Tag bits 7 and 6 set +# 0 0xC0 -- Reserved - a packet tag MUST NOT have this value +# 1 0xC1 -- Public-Key Encrypted Session Key Packet +# 2 0xC2 -- Signature Packet +# 3 0xC3 -- Symmetric-Key Encrypted Session Key Packet +# 4 0xC4 -- One-Pass Signature Packet +# 5 0xC5 -- Secret-Key Packet +# 6 0xC6 -- Public-Key Packet +# 7 0xC7 -- Secret-Subkey Packet +# 8 0xC8 -- Compressed Data Packet +# 9 0xC9 -- Symmetrically Encrypted Data Packet +# 10 0xCA -- Marker Packet +# 11 0xCB -- Literal Data Packet +# 12 0xCC -- Trust Packet +# 13 0xCD -- User ID Packet +# 14 0xCE -- Public-Subkey Packet +# 17 0xD1 -- User Attribute Packet +# 18 0xD2 -- Sym. Encrypted and Integrity Protected Data Packet +# 19 0xD3 -- Modification Detection Code Packet +# 60 to 63 -- Private or Experimental Values +# +# The CTB is followed by the length header, which is densely encoded: +# +# if length[0] is: +# 0..191: one byte length (length[0]) +# 192..223: two byte length ((length[0] - 192) * 256 + length[2] + 192 +# 224..254: four byte length (big endian interpretation of length[1..5]) +# 255: partial body encoding +# +# The partial body encoding is similar to HTTP's chunk encoding. It +# is only allowed for container packets (SEIP, Compressed Data and +# Literal). +# +# Old Style CTB +# ------------- +# +# https://tools.ietf.org/html/rfc4880#section-4.2.1 +# +# CTB: +# +# 76543210 +# ||\--/\/ +# || | length encoding +# || tag +# |always 0 +# always 1 +# +# Tag: +# +# Tag bit 7 set, bits 6, 1, 0 clear +# 0 0x80 -- Reserved - a packet tag MUST NOT have this value +# 1 0x84 -- Public-Key Encrypted Session Key Packet +# 2 0x88 -- Signature Packet +# 3 0x8C -- Symmetric-Key Encrypted Session Key Packet +# 4 0x90 -- One-Pass Signature Packet +# 5 0x94 -- Secret-Key Packet +# 6 0x98 -- Public-Key Packet +# 7 0x9C -- Secret-Subkey Packet +# 8 0xA0 -- Compressed Data Packet +# 9 0xA4 -- Symmetrically Encrypted Data Packet +# 10 0xA8 -- Marker Packet +# 11 0xAC -- Literal Data Packet +# 12 0xB0 -- Trust Packet +# 13 0xB4 -- User ID Packet +# 14 0xB8 -- Public-Subkey Packet +# +# Length encoding: +# +# Value +# 0 1 byte length (following byte is the length) +# 1 2 byte length (following two bytes are the length) +# 2 4 byte length (following four bytes are the length) +# 3 indeterminate length: natural end of packet, e.g., EOF +# +# An indeterminate length is only allowed for container packets +# (SEIP, Compressed Data and Literal). +# +# Certificates +# ------------ +# +# We check the first three packets to determine if a sequence of +# OpenPGP packets is likely to be a certificate. The grammar allows +# the following prefixes: +# +# [Primary Key] [SIG] (EOF or another certificate) +# [Primary Key] [SIG] [User ID] [SIG]... +# [Primary Key] [SIG] [User Attribute] [SIG]... +# [Primary Key] [SIG] [Subkey] [SIG]... +# [Primary Key] [User ID] [SIG]... +# [Primary Key] [User Attribute] [SIG]... +# [Primary Key] [Subkey] [SIG]... +# +# Any number of marker packets are also allowed between each packet, +# but they are not normally used and we don't currently check for +# them. +# +# The keys and subkeys may be public or private. +# + +# Key packets and signature packets are versioned. There are two +# packet versions that we need to worry about in practice: v3 and v4. +# v4 packets were introduced in RFC 2440, which was published in 1998. +# It also deprecated v3 packets. There are no actively used v3 +# certificates (GnuPG removed the code to support them in November +# 2014). But there are v3 keys lying around and it is useful to +# identify them. The next version of OpenPGP will introduce v5 keys. +# The document has not yet been standardized so changes are still +# possible. But, for our purposes, it appears that v5 data structures +# will be identical to v4 data structures modulo the version number. +# +# https://tools.ietf.org/html/rfc2440 +# https://lists.gnupg.org/pipermail/gnupg-announce/2014q4/000358.html +# https://www.ietf.org/id/draft-ietf-openpgp-rfc4880bis-09.html#name-key-material-packet + + + + +# The first packet has to be a public key or a secret key. +# +# New-Style Public Key +0 ubyte =0xC6 OpenPGP Public Key +>&0 use primary_key_length_new +# New-Style Secret Key +0 ubyte =0xC5 OpenPGP Secret Key +>&0 use primary_key_length_new +# Old-Style Public Key +0 ubyte&0xFC =0x98 OpenPGP Public Key +>&-1 use primary_key_length_old +# Old-Style Secret Key +0 ubyte&0xFC =0x94 OpenPGP Secret Key +>&-1 use primary_key_length_old + +# Parse the length, check the packet's body and finally advance to the +# next packet. + +# There are 4 different new-style length encodings, but the partial +# body encoding is only acceptable for the SEIP, Compressed Data, and +# Literal packets, which isn't valid for any packets in a certificate +# so we ignore it. +0 name primary_key_length_new +>&0 ubyte <192 +#>>&0 ubyte x (1 byte length encoding, %d bytes) +>>&0 use pgp_binary_key_pk_check +>>>&(&-1.B) use sig_or_component_1 +>&0 ubyte >191 +>>&-1 ubyte <225 +# offset = ((offset[0] - 192) << 8) + offset[1] + 192 (for the length header) +# raw - (192 * 256 - 192) +# = 48960 +#>>>&0 ubeshort x (2 byte length encoding, %d bytes) +>>>&1 use pgp_binary_key_pk_check +>>>>&(&-2.S-48960) use sig_or_component_1 +>&0 ubyte =255 +#>>&0 belong x (5 byte length encoding, %d bytes) +>>&4 use pgp_binary_key_pk_check +>>>&(&-4.L) use sig_or_component_1 +# Partial body encoding (only valid for container packets). +# >&0 ubyte >224 +# >>&0 ubyte <255 partial body encoding + +# There are 4 different old-style length encodings, but the +# indeterminate length encoding is only acceptable for the SEIP, +# Compressed Data, and Literal packets, which isn't valid for any +# packets in a certificate. +0 name primary_key_length_old +#>&0 ubyte x (ctb: %x) +>&0 ubyte&0x3 =0 +#>>&0 ubyte x (1 byte length encoding, %d bytes) +>>&1 use pgp_binary_key_pk_check +>>>&(&-1.B) use sig_or_component_1 +>&0 ubyte&0x3 =1 +#>>&0 ubeshort x (2 byte length encoding, %d bytes) +>>&2 use pgp_binary_key_pk_check +>>>&(&-2.S) use sig_or_component_1 +>&0 ubyte&0x3 =2 +#>>&0 ubelong x (4 byte length encoding, %d bytes) +>>&4 use pgp_binary_key_pk_check +>>>&(&-4.L) use sig_or_component_1 + +# Check the Key. +# +# https://tools.ietf.org/html/rfc4880#section-5.5.2 +0 name pgp_binary_key_pk_check +# Valid versions are: 2, 3, 4. 5 is proposed in RFC 4880bis. +# Anticipate a v6 / v7 format that like v5 is compatible with v4. +# key format in a decade or so :D. +>&0 ubyte >1 +>>&-1 ubyte <8 +>>>&-1 byte x Version %d +# Check that keys were created after 1990. +# (1990 - 1970) * 365.2524 * 24 * 60 * 60 = 631156147 +>>>&0 bedate >631156147 \b, Created %s +>>>>&-5 ubyte >3 +>>>>>&4 use pgp_binary_key_algo +>>>>&-5 ubyte <4 +>>>>>&6 use pgp_binary_key_algo + +# Print out the key's algorithm and the number of bits, if this is +# relevant (ECC keys are a fixed size). +0 name pgp_binary_key_algo +>0 clear x +>&0 ubyte =1 \b, RSA (Encrypt or Sign, +>>&0 ubeshort x \b %d bits) +>&0 ubyte =2 \b, RSA (Encrypt, +>>&0 ubeshort x \b %d bits) +>&0 ubyte =3 \b, RSA (Sign, +>>&0 ubeshort x \b %d bits) +>&0 ubyte =16 \b, El Gamal (Encrypt, +>>&0 ubeshort x \b %d bits) +>&0 ubyte =17 \b, DSA +>>&0 ubeshort x \b (%d bits) +>&0 ubyte =18 \b, ECDH +>&0 ubyte =19 \b, ECDSA +>&0 ubyte =20 \b, El Gamal (Encrypt or Sign, +>>&0 ubeshort x \b %d bits) +>&0 ubyte =22 \b, EdDSA +>&0 default x +>>&0 ubyte x \b, Unknown Algorithm (%#x) + +# Match all possible second packets. +0 name sig_or_component_1 +#>0 ubyte x (ctb: %x) +>&0 ubyte =0xC2 +>>0 ubyte x \b; Signature +>>&0 use sig_or_component_1_length_new +>&0 ubyte =0xCD +>>0 ubyte x \b; User ID +>>&0 use sig_or_component_1_length_new +>&0 ubyte =0xCE +>>0 ubyte x \b; Public Subkey +>>&0 use sig_or_component_1_length_new +>&0 ubyte =0xC7 +>>0 ubyte x \b; Secret Subkey +>>&0 use sig_or_component_1_length_new +>&0 ubyte =0xD1 +>>0 ubyte x \b; User Attribute +>>&0 use sig_or_component_1_length_new +>&0 ubyte&0xFC =0x88 +>>0 ubyte x \b; Signature +>>&-1 use sig_or_component_1_length_old +>&0 ubyte&0xFC =0xB4 +>>0 ubyte x \b; User ID +>>&-1 use sig_or_component_1_length_old +>&0 ubyte&0xFC =0xB8 +>>0 ubyte x \b; Public Subkey +>>&-1 use sig_or_component_1_length_old +>&0 ubyte&0xFC =0x9C +>>0 ubyte x \b; Secret Subkey +>>&-1 use sig_or_component_1_length_old + +# Copy of 'primary_key_length_new', but calls cert_packet_3. +0 name sig_or_component_1_length_new +>&0 ubyte <192 +#>>&0 ubyte x (1 byte new length encoding, %d bytes) +>>&(&-1.B) use cert_packet_3 +>&0 ubyte >191 +>>&-1 ubyte <225 +# offset = ((offset[0] - 192) << 8) + offset[1] + 192 + 1 (for the length header) +# raw - (192 * 256 - 192 - 1) +# = 48959 +#>>>&-1 ubeshort x (2 byte new length encoding, %d bytes) +>>>&(&-1.S-48959) use cert_packet_3 +>&0 ubyte =255 +#>>&0 belong x (5 byte new length encoding, %d bytes) +>>&(&-4.L) use cert_packet_3 +# Partial body encoding (only valid for container packets). +# >&0 ubyte >224 +# >>&0 ubyte <255 partial body encoding + +0 name sig_or_component_1_length_old +#>&0 ubyte x (ctb: %x) +>&0 ubyte&0x3 =0 +#>>&0 ubyte x (1 byte old length encoding, %d bytes) +>>&(&0.B+1) use cert_packet_3 +>&0 ubyte&0x3 =1 +#>>&0 ubeshort x (2 byte old length encoding, %d bytes) +>>&(&0.S+2) use cert_packet_3 +>&0 ubyte&0x3 =2 +#>>&0 ubelong x (4 byte old length encoding, %d bytes) +>>&(&0.L+4) use cert_packet_3 + +# Copy of above. +0 name cert_packet_3 +#>0 ubyte x (ctb: %x) +>&0 ubyte =0xC2 +>>0 ubyte x \b; Signature +>>&0 use cert_packet_3_length_new +>&0 ubyte =0xCD +>>0 ubyte x \b; User ID +>>&0 use cert_packet_3_length_new +>&0 ubyte =0xCE +>>0 ubyte x \b; Public Subkey +>>&0 use cert_packet_3_length_new +>&0 ubyte =0xC7 +>>0 ubyte x \b; Secret Subkey +>>&0 use cert_packet_3_length_new +>&0 ubyte =0xD1 +>>0 ubyte x \b; User Attribute +>>&0 use cert_packet_3_length_new +>&0 ubyte&0xFC =0x88 +>>0 ubyte x \b; Signature +>>&-1 use cert_packet_3_length_old +>&0 ubyte&0xFC =0xB4 +>>0 ubyte x \b; User ID +>>&-1 use cert_packet_3_length_old +>&0 ubyte&0xFC =0xB8 +>>0 ubyte x \b; Public Subkey +>>&-1 use cert_packet_3_length_old +>&0 ubyte&0xFC =0x9C +>>0 ubyte x \b; Secret Subkey +>>&-1 use cert_packet_3_length_old + +# Copy of above. +0 name cert_packet_3_length_new +>&0 ubyte <192 +#>>&0 ubyte x (1 byte new length encoding, %d bytes) +>>&(&-1.B) use pgp_binary_keys_end +>&0 ubyte >191 +>>&-1 ubyte <225 +# offset = ((offset[0] - 192) << 8) + offset[1] + 192 + 1 (for the length header) +# raw - (192 * 256 - 192 - 1) +# = 48959 +#>>>&-1 ubeshort x (2 byte new length encoding, %d bytes) +>>>&(&-1.S-48959) use pgp_binary_keys_end +>&0 ubyte =255 +#>>&0 belong x (5 byte new length encoding, %d bytes) +>>&(&-4.L) use pgp_binary_keys_end + +0 name cert_packet_3_length_old +#>&0 ubyte x (ctb: %x) +>&0 ubyte&0x3 =0 +#>>&0 ubyte x (1 byte old length encoding, %d bytes) +>>&(&0.B+1) use pgp_binary_keys_end +>&0 ubyte&0x3 =1 +#>>&0 ubeshort x (2 byte old length encoding, %d bytes) +>>&(&0.S+2) use pgp_binary_keys_end +>&0 ubyte&0x3 =2 +#>>&0 ubelong x (4 byte old length encoding, %d bytes) +>>&(&0.L+4) use pgp_binary_keys_end + +# We managed to parse the first three packets of the certificate. Declare +# victory. +0 name pgp_binary_keys_end +>0 byte x \b; OpenPGP Certificate +!:mime application/pgp-keys +!:ext pgp/gpg/pkr/asd |