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74 lines
2.1 KiB
Ruby
74 lines
2.1 KiB
Ruby
# frozen_string_literal: true
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class Multibase
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# Multicodec uses a variable-length unsigned integer to tag
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# data. We precompute here the types we are interested about.
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# Registered types are available at https://github.com/multiformats/multicodec/blob/master/table.csv
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MULTICODEC_PREFIXES = {
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'rsa-pub': 0x1205,
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'ed25519-pub': 0xED,
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'mldsa-44-pub': 0x1210,
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}.transform_values do |code|
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bytes = []
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while code > 127
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bytes << ((code & 0x7F) | 128)
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code >>= 7
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end
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bytes << code
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bytes.pack('C*')
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end.freeze
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ED25519_PUB_DER_HEADER = ['302a300506032b6570032100'].pack('H*').freeze
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ML_DSA_44_PUB_DER_HEADER = ['30820532300b06096086480165030403110382052100'].pack('H*').freeze
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class Error < StandardError; end
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def self.decode(string)
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raise Error, 'Multibase string is nil' if string.nil?
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case string[0]
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when 'u'
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Base64.urlsafe_decode64(string[1...])
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when 'z'
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Base58.base58_to_binary(string[1...], :bitcoin)
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else
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raise Error, 'Invalid Multibase base'
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end
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end
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def self.decode_multicodec(string)
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binary = decode(string)
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MULTICODEC_PREFIXES.each do |tag, prefix|
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return [tag, binary[prefix.length..]] if binary.starts_with?(prefix)
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end
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raise Error, 'Unknown Multicodec tag'
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end
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def self.decode_key_to_pem(string)
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tag, binary = decode_multicodec(string)
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case tag
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when :'rsa-pub'
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[:rsa, OpenSSL::PKey::RSA.new(binary).to_pem]
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when :'ed25519-pub'
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raise Error, 'Invalid data size for ed25519-pub' unless binary.size == 32
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der = ED25519_PUB_DER_HEADER + binary
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[:ed25519, "-----BEGIN PUBLIC KEY-----\n#{Base64.strict_encode64(der)}\n-----END PUBLIC KEY-----\n"]
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when :'mldsa-44-pub'
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raise Error, 'Invalid data size for mldsa-44-pub' unless binary.size == 1312
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der = ML_DSA_44_PUB_DER_HEADER + binary
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[:'ml-dsa-44', "-----BEGIN PUBLIC KEY-----\n#{Base64.strict_encode64(der).scan(/.{,64}/).join("\n")}-----END PUBLIC KEY-----\n"]
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else
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raise Error, 'Unsupported key type'
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end
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rescue OpenSSL::PKey::PKeyError => e
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raise Error, e
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end
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end
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