Topic: How to convert a compressed public key into uncompressed one in Python? (Read 229 times)

import binascii

p = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F

def decompress_pubkey(pk):
    x = int.from_bytes(pk[1:33], byteorder='big')
    y_sq = (pow(x, 3, p) + 7) % p
    y = pow(y_sq, (p + 1) // 4, p)
    if y % 2 != pk[0] % 2:
        y = p - y
    y = y.to_bytes(32, byteorder='big')
    return b'\x04' + pk[1:33] + y

with open('add.txt') as f:
  for line in f:
    line=line.strip()
    print(binascii.hexlify(decompress_pubkey(binascii.unhexlify(line))).decode(),file=open("uncomp.txt", "a"))

def cpub(x,y):
 prefix = '02' if y % 2 == 0 else '03'
 c = prefix+ hex(x)[2:].zfill(64)
 return c
with open('add.txt') as f:
  for line in f:
    line=line.strip()
    x = int(line[2:66], 16)
    y = int(line[66:], 16)
    pub04=cpub(x,y)

    print(pub04,file=open("comp.txt", "a"))

def compressedToUncompressed(compressed_key):
    p = 0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f
    y_parity = int(compressed_key[:2]) - 2
    x = int(compressed_key[2:], 16)
    a = (pow(x, 3, p) + 7) % p
    y = pow(a, (p+1)//4, p)
    if y % 2 != y_parity:
        y = -y % p
    uncompressed_key = '04{:x}{:x}'.format(x, y)
    return uncompressed_key

assert compressedToUncompressed('025A2146590B80D1F0D97CC7104E702011AFFF21BFAF817F5C7002446369BA9DDC') == '045a2146590b80d1f0d97cc7104e702011afff21bfaf817f5c7002446369ba9ddc9bd5dcd1b4a737244d6bb7b96e256391b8597d3a7972a6f8ca9096d4aea1f37e'
assert compressedToUncompressed('035728F4692D85D411DF3643CD69FE05C411A0D507C7D814008F56C8F260AD7ED9') == '045728f4692d85d411df3643cd69fe05c411a0d507c7d814008f56c8f260ad7ed99e2df8d9cb1a575d55264692629ae22e518bc14ad02592941c13be6755c72973'
assert compressedToUncompressed('039E87EB177890FDD788B95843ED53AD4FB6E877E3F730EF1E73593964C2AB9D15') == '049e87eb177890fdd788b95843ed53ad4fb6e877e3f730ef1e73593964c2ab9d15a3b647c8c4a0766420917b7b445cdcd6bfec2900175c5534c6113954f3ff00d9'

045a2146590b80d1f0d97cc7104e702011afff21bfaf817f5c7002446369ba9ddc9bd5dcd1b4a737244d6bb7b96e256391b8597d3a7972a6f8ca9096d4aea1f37e

045728f4692d85d411df3643cd69fe05c411a0d507c7d814008f56c8f260ad7ed99e2df8d9cb1a575d55264692629ae22e518bc14ad02592941c13be6755c72973

049e87eb177890fdd788b95843ed53ad4fb6e877e3f730ef1e73593964c2ab9d15a3b647c8c4a0766420917b7b445cdcd6bfec2900175c5534c6113954f3ff00d9

042351126323155009915566305515988222562668831973356296881287277305661165837788ee29766cfd677f845e830bea820e1ef951b86fdc335247a8aa697e6baf1ef78

046799846282981021315422058923075594964980219729412475060169781627609169100505f87b4bda8ed8b93cff4207e66c65b4909a48a3b54076aac6d6ba7626e15ba875

049081844685017147717691639198226214703337765349173402524026447080150572702997d7b2db226c460a5e7167c150fab386c8688dd4170d3d453a2c3efad529c73e75

045a2146590b80d1f0d97cc7104e702011afff21bfaf817f5c7002446369ba9ddc9bd5dcd1b4a737244d6bb7b96e256391b8597d3a7972a6f8ca9096d4aea1f37e

045728f4692d85d411df3643cd69fe05c411a0d507c7d814008f56c8f260ad7ed99e2df8d9cb1a575d55264692629ae22e518bc14ad02592941c13be6755c72973

049e87eb177890fdd788b95843ed53ad4fb6e877e3f730ef1e73593964c2ab9d15a3b647c8c4a0766420917b7b445cdcd6bfec2900175c5534c6113954f3ff00d9

#Test case 1
#Compressed Pubkey: 025A2146590B80D1F0D97CC7104E702011AFFF21BFAF817F5C7002446369BA9DDC
'''
Right Uncompressed Pubkey:
045A2146590B80D1F0D97CC7104E702011AFFF21BFAF817F5C7002446369BA9DDC9BD5DCD1B4A737244D6BB7B96E256391B8597D3A7972A6F8CA9096D4AEA1F37E
'''

#Test case 2
#Compressed Pubkey: 035728F4692D85D411DF3643CD69FE05C411A0D507C7D814008F56C8F260AD7ED9
'''
Right Uncompressed Pubkey:
045728F4692D85D411DF3643CD69FE05C411A0D507C7D814008F56C8F260AD7ED99E2DF8D9CB1A575D55264692629AE22E518BC14AD02592941C13BE6755C72973
'''

#Test case 3
#Compressed Pubkey:039E87EB177890FDD788B95843ED53AD4FB6E877E3F730EF1E73593964C2AB9D15
'''
Right Uncompressed Pubkey:
049E87EB177890FDD788B95843ED53AD4FB6E877E3F730EF1E73593964C2AB9D15A3B647C8C4A0766420917B7B445CDCD6BFEC2900175C5534C6113954F3FF00D9