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August 31, 2021 12:55
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How to decrypt a PKCS7 in Crystal using OpenSSL
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# shard.yml | |
# dependencies: | |
# openssl_ext: | |
# github: spider-gazelle/openssl_ext | |
# version: ~> 2.0 | |
require "openssl" | |
require "openssl_ext" | |
ciphertext = "-----BEGIN CERTIFICATE----- | |
MIIBiQYJKoZIhvcNAQcDoIIBejCCAXYCAQAxggEhMIIBHQIBAD | |
AFMAACAQEwDQYJKoZIhvcNAQEBBQAEggEAXW6UXSjJb2QBw4qqVF/CMHkeJE | |
t/J15ra2XRvlR09yICgof7r9B9pB1SlmZrgi5ar1NIkYwZ1h8dWNMkKthpQk | |
X57iJ+/+XO/UuK8qcuen/oUajcJZOs6o5udob0mrJsp5d4MZczSc4IrERAlJ | |
brNAsdnxp83U8AGxlBeKCnu+fetC1DAD2QZ2vf9qioH/7EKloA2bCIgrKe1U | |
EkhMR0i8DlfTVm+uYfA8o4u95Sc9UkpPlGwXXEJRDK+0WXh8xhmjmcfrOfWI | |
wvddTn9EQ8CHETCGPp8Hhr51TC1+voq6ODuDcrIdgWyjRsZWVsis9UVQ83lV | |
oKsyZt8KU3dnq7gTBMBgkqhkiG9w0BBwEwHQYJYIZIAWUDBAEqBBAEsrizxa | |
LubBPdDuVG6Fv/gCCOF+YlrZNFo3TaWpnQe4NCrSmLfHdVvkkaxgE1JLAYfA | |
== | |
-----END CERTIFICATE-----" | |
public_key = "./keys/public_key.pkcs7.pem" | |
private_key = "./keys/private_key.pkcs7.pem" | |
private_key_pem = File.read private_key | |
private_key_rsa = OpenSSL::PKey::RSA.new(private_key_pem) | |
public_key_pem = File.read public_key | |
public_key_x509 = OpenSSL::X509::Certificate.new(public_key_pem) | |
lib LibCrypto | |
type PKCS7 = Void* | |
fun pem_read_bio_pkcs7 = PEM_read_bio_PKCS7(bp : Bio*, x : PKCS7*, cb : PasswordCallback, u : Void*) : PKCS7 | |
fun pkcs7_decrypt = PKCS7_decrypt(p7 : PKCS7, pkey : EvpPKey*, cert : X509, data : Bio*, flags : Int32) : Int32 | |
end | |
class OpenSSL::PKCS7 | |
def initialize(@ciphertext : String) | |
io = IO::Memory.new(@ciphertext) | |
bio = OpenSSL::GETS_BIO.new(io) | |
@pkcs7 = LibCrypto.pem_read_bio_pkcs7(bio, nil, nil, nil) | |
end | |
def decrypt(private_key_rsa : OpenSSL::PKey::RSA, public_key_x509 : OpenSSL::X509::Certificate) | |
key = private_key_rsa | |
x509 = public_key_x509 | |
data = OpenSSL::MemBIO.new | |
flg = 0 | |
ret_code = LibCrypto.pkcs7_decrypt(@pkcs7, key, x509, data, 0) | |
data.to_string | |
end | |
end | |
pkcs7 = OpenSSL::PKCS7.new(ciphertext) | |
puts pkcs7.decrypt(private_key_rsa, public_key_x509) |
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