Module: NwcRuby::NIP04::Cipher

Defined in:
lib/nwc_ruby/nip04/cipher.rb

Overview

NIP-04: legacy DM encryption. AES-256-CBC, PKCS7 padding, random 16-byte IV. Key is the raw ECDH X coordinate (no hashing). Payload format: “<base64_ciphertext>?iv=<base64_iv>”

Deprecated in general, but still required for NWC because many wallet services have not migrated: they emit NIP-04 requests/responses (kind 23194/23195) and NIP-04 notifications (kind 23196) alongside or instead of NIP-44 v2.

Class Method Summary collapse

Class Method Details

.decrypt(payload, privkey_hex, pubkey_hex) ⇒ Object 



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# File 'lib/nwc_ruby/nip04/cipher.rb', line 28

def decrypt(payload, privkey_hex, pubkey_hex)
  raise EncryptionError, 'malformed NIP-04 payload' unless payload.include?('?iv=')

  ct_b64, iv_b64 = payload.split('?iv=', 2)
  ct = Base64.strict_decode64(ct_b64)
  iv = Base64.strict_decode64(iv_b64)
  raise EncryptionError, 'invalid IV length' unless iv.bytesize == 16

  key = Crypto::ECDH.shared_x(privkey_hex, pubkey_hex)

  cipher = OpenSSL::Cipher.new('aes-256-cbc').decrypt
  cipher.key = key
  cipher.iv  = iv
  (cipher.update(ct) + cipher.final).force_encoding('UTF-8')
rescue OpenSSL::Cipher::CipherError, ArgumentError => e
  raise EncryptionError, "NIP-04 decryption failed: #{e.message}"
end

.encrypt(plaintext, privkey_hex, pubkey_hex) ⇒ Object 



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# File 'lib/nwc_ruby/nip04/cipher.rb', line 16

def encrypt(plaintext, privkey_hex, pubkey_hex)
  key = Crypto::ECDH.shared_x(privkey_hex, pubkey_hex)
  iv  = SecureRandom.bytes(16)

  cipher = OpenSSL::Cipher.new('aes-256-cbc').encrypt
  cipher.key = key
  cipher.iv  = iv
  ct = cipher.update(plaintext.encode('UTF-8')) + cipher.final

  "#{Base64.strict_encode64(ct)}?iv=#{Base64.strict_encode64(iv)}"
end