---
name: "Crypt::PK::RSA"
section: "3pm"
platform: "linux"
package: "perl-cryptx"
version: "0.091-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Crypt::PK::RSA"
---

# Crypt::PK::RSA(3pm)

Public key cryptography based on RSA

## NAME

Crypt::PK::RSA - Public key cryptography based on RSA

## SYNOPSIS

```
 ### OO interface
 my $message = 'hello world';
 my $private_key = Crypt::PK::RSA->new();
 $private_key->generate_key(256, 65537);
 my $public_der = $private_key->export_key_der('public');
 my $public_key = Crypt::PK::RSA->new(\$public_der);
 my $ciphertext = $public_key->encrypt($message);
 my $plaintext = $private_key->decrypt($ciphertext);
 my $signature = $private_key->sign_message($message, 'SHA256');
 $public_key->verify_message($signature, $message, 'SHA256') or die "ERROR";
 my $private_der = $private_key->export_key_der('private');
 my $private_pem = $private_key->export_key_pem('private');
 my $public_pem = $public_key->export_key_pem('public');
```

## DESCRIPTION

The module provides a full featured RSA implementation.

Legacy function-style wrappers still exist in code for backwards compatibility, but they are intentionally undocumented.

## METHODS

### new

```
  my $source = Crypt::PK::RSA->new();
  $source->generate_key(256, 65537);
  my $public_der = $source->export_key_der('public');
  my $pub = Crypt::PK::RSA->new(\$public_der);
  my $private_pem = $source->export_key_pem('private', 'secret', 'AES-256-CBC');
  my $priv = Crypt::PK::RSA->new(\$private_pem, 'secret');
```

Passing `$filename` or `"\$buffer"` to `"new"` is equivalent: both forms immediately import the key material into the new object.

### generate\_key

Uses the bundled `"chacha20"` PRNG via libtomcrypt's `"rng_make_prng"`. Returns the object itself (for chaining).

```
 $pk->generate_key($size, $e);
 # $size .. [integer] key size: 128-512 bytes (DEFAULT is 256)
 # $e ..... [integer] exponent: 3, 17, 257 or 65537 (DEFAULT is 65537)
```

The `$size` and `$e` arguments use Perl's usual numeric-to-integer coercion before reaching the XS layer. Pass exact integers; values like `10.9` or `"1e2"` are coerced rather than rejected.

### import\_key

Loads private or public key in DER or PEM format.

```
  my $source = Crypt::PK::RSA->new();
  $source->generate_key(256, 65537);
  my $public_der = $source->export_key_der('public');
  my $pub = Crypt::PK::RSA->new();
  $pub->import_key(\$public_der);
  my $private_pem = $source->export_key_pem('private', 'secret', 'AES-256-CBC');
  my $priv = Crypt::PK::RSA->new();
  $priv->import_key(\$private_pem, 'secret');
```

The same method also accepts filenames instead of buffers.

Loading private or public keys from a Perl HASH:

```
 $pk->import_key($hashref);
 # the $hashref is either a key exported via key2hash
 $pk->import_key({
   e  => "10001", #public exponent
   d  => "9ED5C3D3F866E06957CA0E9478A273C39BBDA4EEAC5B...", #private exponent
   N  => "D0A5CCCAE03DF9C2F5C4C8C0CE840D62CDE279990DC6...", #modulus
   p  => "D3EF0028FFAB508E2773C659E428A80FB0E9211346B4...", #p factor of N
   q  => "FC07E46B163CAB6A83B8E467D169534B2077DCDEECAE...", #q factor of N
   qP => "88C6D406F833DF73C8B734548E0385261AD51F4187CF...", #1/q mod p CRT param
   dP => "486F142FEF0A1F53269AC43D2EE4D263E2841B60DA36...", #d mod (p - 1) CRT param
   dQ => "4597284B2968B72C4212DB7E8F24360B987B80514DA9...", #d mod (q - 1) CRT param
 });
 # or a hash with items corresponding to JWK (JSON Web Key)
 $pk->import_key({
   kty => "RSA",
   n   => "0vx7agoebGcQSuuPiLJXZpt...eZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
   e   => "AQAB",
   d   => "X4cTteJY_gn4FYPsXB8rdXi...FLN5EEaG6RoVH-HLKD9Mdx5ooGURknhnrRwUkC7h5fJLMWbFAKLWY2v7B6NqSzUvx0_YSf",
   p   => "83i-7IvMGXoMXCskv73TKr8...Z27zvoj6pbUQyLPBQxtPnwD20-60eTmD2ujMt5PoMrm8RmNhVWtjjMmMjOpSicFHjXOuVI",
   q   => "3dfOR9cuYq-0S-mkFLzgItg...q3hWeMuG0ouqnb3obLyuqjVZQ1dIrdgTnCdYzBcOW5r37AFXjift_NGiovonzhKpoVVS78",
   dp  => "G4sPXkc6Ya9y8oJW9_ILj4...zi_H7TkS8x5SdX3oE0oiYwxIiemTAu0UOa5pgFGyJ4c8t2VF40XRugKTP8akhFo5tA77Qe",
   dq  => "s9lAH9fggBsoFR8Oac2R_E...T2kGOhvIllTE1efA6huUvMfBcpn8lqW6vzzYY5SSF7pMd_agI3G8IbpBUb0JiraRNUfLhc",
   qi  => "GyM_p6JrXySiz1toFgKbWV...4ypu9bMWx3QJBfm0FoYzUIZEVEcOqwmRN81oDAaaBk0KWGDjJHDdDmFW3AN7I-pux_mHZG",
 });
```

Supported key formats:

```
 # all formats can be loaded from a file
 my $pk = Crypt::PK::RSA->new($filename);
 # or from a buffer containing the key
 my $pk = Crypt::PK::RSA->new(\$buffer_with_key);
```

- •

  RSA public keys

  ```
   -----BEGIN PUBLIC KEY-----
   MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDHlYKg9DeHB3/dY1D9WCyJTnl5
   vEzAXpUOL9tDtdPUl96brIbbdMLooO1hKjsq98kLs1q4vOn/pxvzk0BRwhiu7Vvb
   VUjAn/2HHDDL0U1utqqlMJhaffeLI3HEq5o/lSMFY7sSkZU/E4YX1yqAN0SE7xfK
   B2uzcNq60sMIfp6siQIDAQAB
   -----END PUBLIC KEY-----
  ```

- •

  RSA private keys

  ```
   -----BEGIN RSA PRIVATE KEY-----
   MIICXQIBAAKBgQDHlYKg9DeHB3/dY1D9WCyJTnl5vEzAXpUOL9tDtdPUl96brIbb
   dMLooO1hKjsq98kLs1q4vOn/pxvzk0BRwhiu7VvbVUjAn/2HHDDL0U1utqqlMJha
   ffeLI3HEq5o/lSMFY7sSkZU/E4YX1yqAN0SE7xfKB2uzcNq60sMIfp6siQIDAQAB
   AoGBAI5+GgNcGQDYw9uF+t7FwxZM5sGZRJrbbEPyuvL+sDxKKW6voKCyHi4EJzaF
   9jRZMDqgVJcsmUwjPPuMGBHHJ+MI5Zb3L0jbZkyx8u+U5gf88oy9eZmfGOjmHcMB
   oCgzyoLmJETuyADg2onLanuY3jggFb3tq/jimKjO8xM2R6zhAkEA7uXWWyJI9cCN
   zrVt5R5v6oosjZ4r5VILGMqBRLrzfTvH+WDMK6Rl/2MHE+YDeLajzunaM8qY2456
   GTYEXQsIdQJBANXfMEtXocSdPtoVj3ME8Do/0r+ApgTdcDPCwXOzkmkEJW/UFMSn
   b8CYF5G6sZQN9L5z3s2nvi55PaFV8Q0LMUUCQBh9GvIQm6YFbQPpeTBpZFOIgnSp
   6BoDxPtvlryy5U7LF/6qO4OlwIbjYdBaXbS8FCKbujBg7jZjboSzEtNu1BkCQDGT
   w0Yz0jQZn3A+fzpScr2N/fSWheWqz0+wXdfMUKw3YdZCe236wlUK7KvDc1a2xX1A
   ru1NbTCoujikC3TSm2ECQQDKQshchJlZJmFv9vCFQlGCA/EX+4406xvOOiixbPYC
   pIB4Ee2cmvEdAqSaOjrvgs5zvaCCFBO0MecPStCAxUX6
   -----END RSA PRIVATE KEY-----
  ```

- •

  RSA private keys in password protected PEM format

  ```
   -----BEGIN RSA PRIVATE KEY-----
   Proc-Type: 4,ENCRYPTED
   DEK-Info: DES-EDE3-CBC,4D697440FF5AEF18
   C09H49Gn99o8b8O2r4+Hqao4r3udvC+QSSfsk20sXatyuZSEmbhyqKAB+13NRj+3
   KIsRTqnL9VkeibIGgLHuekOFKAqeSVZ0PmR4bGWEFxUPAYUvg9N9pIa6hGtNZG+y
   TEpOAfFITb1pbHQhp3j8y7qmKc5kY5LrZSFE8WwA24NTG773E07wJgRxKDkXNGOl
   kki6oYArNEps0DdtHFxzgdRg0+yaotXuFJRuC5V4YzKGG/oSRcgYyXKTwCndb3xt
   aHgI2WprQAPg+qOpLABzoi7bEjCqbHWrwkvnAngylbim2Uyvw1e1xKnzlgIHU7pv
   e/J+s00pTItfqW1IpY2mh4C9nkfkfVKBKaAv7jO0s6aPySATqsdlrzv2kpF6Ub4J
   kgaZDOfZ4K3qkyAYVLWcQeDqg4glv9Ah2J05bTm4qrIMmthYnThyQlGvcjUfCMXs
   0t+mEQbsRY7xKt0o6HzzvQlJ+JsFlLORoslAubJX9iLqpEdnlrj1lD9bo6uIClZ5
   5+aoLcAyz1D4OsauuP5i8VFu+Is+QG4SN/vHVuArjkqi3VpLwSAjNDY+KWbq042l
   CqlM2mwm6FIGUZQFxiLHJD7WDmk1xmae++m+XG9CEDTfrUQ5v+l0O6BTrl80XUfU
   w3gzAWbSjz3UK0FpKeABVFPE9fjNP9fTcS6qL5YJWBPflwxCAbVgsBOW4bOMpDGK
   BJDQTeShWn4BlYCe/vgThI9ERdgZhRz4NcFeDgVA/CqQzVqptvz4PSqH46fqUN2n
   4PtJgKE5cASYUBuAjlD71FecSVVM/OTzL1uxYzXBilzvVn2vSHgo9g==
   -----END RSA PRIVATE KEY-----
  ```

- •

  PKCS#8 encoded private keys

  ```
   -----BEGIN PRIVATE KEY-----
   MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBANPN17xW4EkH5PXG
   1i/i3rE1EXFcCHyxmz95VRBDs1p3MuYf9mxntbfYAmuzS3KrRWh3IyX/Eh80N/v9
   OXPlwZbVqSTX+L3pCEJtRtsWn0zmswGThjMZiwle0oWuap63L35F1QN8EDaSPSBC
   yGELNRr6rwVYq0w5b+LOcaCZ+/H1AgMBAAECgYEApfu3aGpww+rC3HUhX0+ckyTy
   cXLdV9LbxidwqRlVEb0+DyfXNucjelp2sy5EHy3na9GJovo8mmWSxhCRGKliRkQ6
   XgrEMZdCSaWI2AazuHAGlUJRFEVkvdla3AuBAn6y0YdDp/3kbg0yahmKyD8Gq74z
   nUYbDL3R5JtR2Ad/KlUCQQDvSEICTHbO/BF7hVmlKRYZSNHKEPrv8X/OlppS14Kv
   QRwc+CZ5+l6T1Y+l5cHJQUXrXZoWS1K741TXdUhjjUd7AkEA4pod804Ex8sttdWi
   pHMfeyj+IbPAk5XnBc91jT7AYIeL8ccjtfl99xhMsGFaxrh3wA/4SGEvwzWkbxcq
   H8G5TwJAKNG+0P2SVwURRm0dOdukdXPCtiHnbP9Zujhe4zr4hEUrMpXymmRntfh8
   pORpBpgoAVraams3Fe5WDttnGfSD+QJAOOC6V9HjfUrQhG3FT0XeRwm5EDiQQ/tC
   a8DxHqz7mL8tL1ju68ReC+G7jiJBqNOwqzLW/UP3uyYByiikWChGHQJAHUau7jIM
   45ErO096n94Vh95p76ANxOroWszOt39TyvJOykIfoPwFagLrBWV9Jjos2/D54KE+
   fyoy4t3yHT+/nw==
   -----END PRIVATE KEY-----
  ```

- •

  PKCS#8 encrypted private keys - password protected keys (supported since: CryptX-0.062)

  ```
   -----BEGIN ENCRYPTED PRIVATE KEY-----
   MIICojAcBgoqhkiG9w0BDAEDMA4ECCQk+Rr1yzzcAgIIAASCAoD/mgpUFjxxM/Ty
   Yt+NeT0Fo4echgoGksqs6+rYhO16oshG664emZfkuNoFGGzJ38X6GVuqIXhlPnYQ
   biKvL37dN/KnoGytFHq9Wnk8dDwjGHPtwajhW5WuIV3NuhW/AO1PF/cRZKFjWrPt
   NWY5CrpfH6t6zojoe+5uyXpH29lQy4OqvSRdPIt/12UcB+tzV7XzSWEuXh8HAi8a
   sYUu6tuCFnq4GrD2ffM4KWFmL5GqBAwN6m0KkyrNni9XT+RaA6zEhv/lVcwg2esa
   4/EzRs0ixzzZDKaml8oCMl9RHtFAbQmdlfV7Ip4rGK9BwY6UFiDMIVru6HynOVQK
   vvZ+j//bgO+3ubrv7psX+vC9Fy/MoH2Tc7MIwDN/QVTciPZlzjWBnBNxMfeFKtEn
   d7NFiapgfLuRQIiDTMrW/clcqvO54NphxhrcgUEoxos4twKZARntqPZHtf8nEM2x
   2sEF5kI65aEF/5Yy16qvP0vZAA2B1kcIdXZ8XLZCp4c3olhkIrmgUpo1gyFXdCoC
   7dT5Cz7/YLkq5hkcFrtp4V9BZMR24fSttc4p24N5xuZ+JneGnGkLX6B+nJAtm9vw
   bZA6P+23GI0qeMzL3HJXwCOTSsWfm/H9W5+2Zmw851aAmE+pZLni/pk3e3iNSWgs
   946x/doA5O0uCFsU7oxme+WAIp2SjhxGoe808Lf1CCFMPboFi1O/E0NsX8SIEX+i
   U+UHi4kxZqVkr3Q5SB/9kiSv8K1bE787yueQOT/dsTYYaMsjAbkEZo0o/47F32T6
   A2ioXHOV/pr5zNHqE5tL+qKEcLYbAUF1O+WvmdqYz+vHQjRQBatAqTmncvLDYr/j
   1HPwZX2d
   -----END ENCRYPTED PRIVATE KEY-----
  ```

- •

  RSA public key from X509 certificate

  ```
   -----BEGIN CERTIFICATE-----
   MIIC8zCCAdugAwIBAgIJAPi+LvMU3uGWMA0GCSqGSIb3DQEBCwUAMBAxDjAMBgNV
   BAMMBXBva3VzMB4XDTE3MDcxNDE0MTAyMFoXDTIwMDQwOTE0MTAyMFowEDEOMAwG
   A1UEAwwFcG9rdXMwggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDCQima
   SUIMIdz5uVevzcScbcj06xs1OLaFKUoPJ8v+xP6Ut61BQhAvc8GYuw2uRx223hZC
   r3HYLfSdWIfmOIAtlL8cPYPVoSivJtpSGE6fBG1tlBjVgXWRmJGR/oxx6Y5QDwcB
   Q4GZKga8TtHQoY5idZuatYOFZGfMIcIUC0Uoda+YSypnw7A90F/JvlpcTUh3Fnem
   VinqEA6XOegU9dCZk/29sXqauBjbdGihh8DvpklOhY16eQoiR3909AywQ0KUmI+R
   Sa9E8oIsmUDetFuXEvana+sD3y42tU+cd2nhBPRETbSXPcum0B3uF4yKgweuJy5D
   cvtVQIFVkkh4+AWNAgMBAAGjUDBOMB0GA1UdDgQWBBSS6V5PVGyN92NoB0AVLcOb
   pzR3SzAfBgNVHSMEGDAWgBSS6V5PVGyN92NoB0AVLcObpzR3SzAMBgNVHRMEBTAD
   AQH/MA0GCSqGSIb3DQEBCwUAA4IBAQBIszrBjoJ39axsS6Btbvwvo8vAmgiSWsav
   7AmjXOAwknHPaCcDmrdOys5POD0DNRwNeRsnxFiZ/UL8Vmj2JGDLgAw+/v32MwfX
   Ig7m+oIbO8KqDzlYvS5kd3suJ5C21hHy1/JUtfofZLovZH7ZRzhTAoRvCYaodW90
   2o8ZqmyCdcXPzjFmoJ2xYzs/Sf8/E1cHfb+4HjOpeRnKxDvG0gwWzcsXpUrw2pNO
   Oztj6Rd0THNrf/anIeYVtAHX4aqZA8Kbv2TyJd+9g78usFw1cn+8vfmilm6Pn0DQ
   a+I5GyGd7BJI8wYuWqIStzvrJHbQQaNrSk7hgjWYiYlcsPh6w2QP
   -----END CERTIFICATE-----
  ```

- •

  SSH public RSA keys

  ```
   ssh-rsa AAAAB3NzaC1yc2EAAAADAQA...6mdYs5iJNGu/ltUdc=
  ```

- •

  SSH public RSA keys (RFC-4716 format)

  ```
   ---- BEGIN SSH2 PUBLIC KEY ----
   Comment: "768-bit RSA, converted from OpenSSH"
   AAAAB3NzaC1yc2EAAAADAQABAAAAYQDYebeGQFCnlQiNRE7r9UEbjr+DQMTdw1ZHGB2w6x
   D/DzKem8761GdCpqsLrGaw2D7aSIoP1B5Sz870YoVWHn6Ao7Hvm17V3Kxfn4B01GNQTM5+
   L26mdYs5iJNGu/ltUdc=
   ---- END SSH2 PUBLIC KEY ----
  ```

- •

  RSA private keys in JSON Web Key (JWK) format

  See \<https://www.rfc-editor.org/rfc/rfc7517\>

  ```
   {
     "kty":"RSA",
     "n":"0vx7agoebGcQSuuPiLJXZpt...eZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
     "e":"AQAB",
     "d":"X4cTteJY_gn4FYPsXB8rdXi...FLN5EEaG6RoVH-HLKD9Mdx5ooGURknhnrRwUkC7h5fJLMWbFAKLWY2v7B6NqSzUvx0_YSf",
     "p":"83i-7IvMGXoMXCskv73TKr8...Z27zvoj6pbUQyLPBQxtPnwD20-60eTmD2ujMt5PoMrm8RmNhVWtjjMmMjOpSicFHjXOuVI",
     "q":"3dfOR9cuYq-0S-mkFLzgItg...q3hWeMuG0ouqnb3obLyuqjVZQ1dIrdgTnCdYzBcOW5r37AFXjift_NGiovonzhKpoVVS78",
     "dp":"G4sPXkc6Ya9y8oJW9_ILj4...zi_H7TkS8x5SdX3oE0oiYwxIiemTAu0UOa5pgFGyJ4c8t2VF40XRugKTP8akhFo5tA77Qe",
     "dq":"s9lAH9fggBsoFR8Oac2R_E...T2kGOhvIllTE1efA6huUvMfBcpn8lqW6vzzYY5SSF7pMd_agI3G8IbpBUb0JiraRNUfLhc",
     "qi":"GyM_p6JrXySiz1toFgKbWV...4ypu9bMWx3QJBfm0FoYzUIZEVEcOqwmRN81oDAaaBk0KWGDjJHDdDmFW3AN7I-pux_mHZG",
   }
  ```

  **BEWARE:** For JWK support you need to have JSON module installed.

- •

  RSA public keys in JSON Web Key (JWK) format

  ```
   {
     "kty":"RSA",
     "n": "0vx7agoebGcQSuuPiLJXZp...tN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECP",
     "e":"AQAB",
   }
  ```

  **BEWARE:** For JWK support you need to have JSON module installed.

### export\_key\_der

Returns the key as a binary DER-encoded string.

```
 my $private_der = $pk->export_key_der('private');
 #or
 my $public_der = $pk->export_key_der('public');
```

### export\_key\_pem

Returns the key as a PEM-encoded string (ASCII).

```
 my $private_pem = $pk->export_key_pem('private');
 #or
 my $public_pem = $pk->export_key_pem('public');
 #or
 my $public_pem = $pk->export_key_pem('public_x509');
```

With parameter `'public'` uses header and footer lines:

```
  -----BEGIN RSA PUBLIC KEY------
  -----END RSA PUBLIC KEY------
```

With parameter `'public_x509'` uses header and footer lines:

```
  -----BEGIN PUBLIC KEY------
  -----END PUBLIC KEY------
```

Support for password protected PEM keys

```
 my $private_pem = $pk->export_key_pem('private', $password);
 #or
 my $private_pem = $pk->export_key_pem('private', $password, $cipher);
 # supported ciphers: 'DES-CBC'
 #                    'DES-EDE3-CBC'
 #                    'SEED-CBC'
 #                    'CAMELLIA-128-CBC'
 #                    'CAMELLIA-192-CBC'
 #                    'CAMELLIA-256-CBC'
 #                    'AES-128-CBC'
 #                    'AES-192-CBC'
 #                    'AES-256-CBC' (DEFAULT)
```

### export\_key\_jwk

*Since: CryptX-0.022*

Returns a JSON string, or a hashref if the optional second argument is true.

Exports public/private keys as a JSON Web Key (JWK).

```
 my $private_json_text = $pk->export_key_jwk('private');
 #or
 my $public_json_text = $pk->export_key_jwk('public');
```

Also exports public/private keys as a Perl HASH with JWK structure.

```
 my $jwk_hash = $pk->export_key_jwk('private', 1);
 #or
 my $jwk_hash = $pk->export_key_jwk('public', 1);
```

**BEWARE:** For JWK support you need to have JSON module installed.

### export\_key\_jwk\_thumbprint

*Since: CryptX-0.031*

Exports the key's JSON Web Key Thumbprint as a string.

If you don't know what this is, see RFC 7638 \<https://www.rfc-editor.org/rfc/rfc7638\>.

```
 my $thumbprint = $pk->export_key_jwk_thumbprint('SHA256');
```

### encrypt

Returns the ciphertext as a binary string.

```
 my $pk = Crypt::PK::RSA->new($pub_key_filename);
 my $ct = $pk->encrypt($message);
 #or
 my $ct = $pk->encrypt($message, $padding);
 #or
 my $ct = $pk->encrypt($message, 'oaep', $hash_name, $lparam);
 # $padding .................... [string] 'oaep' (DEFAULT), 'v1.5' or 'none' (INSECURE)
 # $hash_name (only for oaep) .. [string] 'SHA1' (DEFAULT), 'SHA256' or any other hash supported by Crypt::Digest
 # $lparam (only for oaep) ..... [binary string] DEFAULT is empty string
```

### decrypt

Returns the plaintext as a binary string.

```
 my $pk = Crypt::PK::RSA->new($priv_key_filename);
 my $pt = $pk->decrypt($ciphertext);
 #or
 my $pt = $pk->decrypt($ciphertext, $padding);
 #or
 my $pt = $pk->decrypt($ciphertext, 'oaep', $hash_name, $lparam);
 # $padding .................... [string] 'oaep' (DEFAULT), 'v1.5' or 'none' (INSECURE)
 # $hash_name (only for oaep) .. [string] 'SHA1' (DEFAULT), 'SHA256' or any other hash supported by Crypt::Digest
 # $lparam (only for oaep) ..... [binary string] DEFAULT is empty string
```

### sign\_message

Returns the signature as a binary string.

```
 my $pk = Crypt::PK::RSA->new($priv_key_filename);
 my $signature = $pk->sign_message($message);
 #or
 my $signature = $pk->sign_message($message, $hash_name);
 #or
 my $signature = $pk->sign_message($message, $hash_name, $padding);
 #or
 my $signature = $pk->sign_message($message, $hash_name, 'pss', $saltlen);
 # $hash_name ............... [string] 'SHA1' (DEFAULT, INSECURE), 'SHA256' or any other hash supported by Crypt::Digest
 # $padding ................. [string] 'pss' (DEFAULT) or 'v1.5' or 'none' (INSECURE)
 # $saltlen (only for pss) .. [integer] DEFAULT is 12
```

**BEWARE:** The `$hash_name` default is `'SHA1'` only for backward compatibility. SHA-1 is vulnerable to practical collision attacks and is not safe for signing messages whose content may be influenced by an attacker. Always pass an explicit hash name such as `'SHA256'`. The same applies to "verify\_message", "sign\_hash" and "verify\_hash".

For RSASSA-PSS with SHAKE per RFC 8702 \<https://www.rfc-editor.org/rfc/rfc8702\> use `'SHAKE128'` (output 32 bytes, `$saltlen` = 32) or `'SHAKE256'` (output 64 bytes, `$saltlen` = 64); both the message hash and the internal MGF use SHAKE directly as defined by RFC 8702.

```
 my $sig = $pk->sign_message($message, 'SHAKE128', 'pss', 32);  # id-RSASSA-PSS-SHAKE128
 my $sig = $pk->sign_message($message, 'SHAKE256', 'pss', 64);  # id-RSASSA-PSS-SHAKE256
```

### verify\_message

Returns `1` if the signature is valid, `0` otherwise.

```
 my $pk = Crypt::PK::RSA->new($pub_key_filename);
 my $valid = $pk->verify_message($signature, $message);
 #or
 my $valid = $pk->verify_message($signature, $message, $hash_name);
 #or
 my $valid = $pk->verify_message($signature, $message, $hash_name, $padding);
 #or
 my $valid = $pk->verify_message($signature, $message, $hash_name, 'pss', $saltlen);
 # $hash_name ............... [string] 'SHA1' (DEFAULT, INSECURE), 'SHA256' or any other hash supported by Crypt::Digest
 # $padding ................. [string] 'pss' (DEFAULT) or 'v1.5' or 'none' (INSECURE)
 # $saltlen (only for pss) .. [integer] DEFAULT is 12
```

### sign\_hash

Returns the signature as a binary string.

```
 my $pk = Crypt::PK::RSA->new($priv_key_filename);
 my $signature = $pk->sign_hash($message_hash);
 #or
 my $signature = $pk->sign_hash($message_hash, $hash_name);
 #or
 my $signature = $pk->sign_hash($message_hash, $hash_name, $padding);
 #or
 my $signature = $pk->sign_hash($message_hash, $hash_name, 'pss', $saltlen);
 #or
 my $signature = $pk->sign_hash($message_hash, $hash_name, 'pss', $saltlen, $mgf_hash_name);
 # $hash_name ................. [string] 'SHA1' (DEFAULT, INSECURE), 'SHA256' or any other hash supported by Crypt::Digest
 # $padding ................... [string] 'pss' (DEFAULT) or 'v1.5' or 'none' (INSECURE)
 # $saltlen (pss only) ........ [integer] DEFAULT is 12
 # $mgf_hash_name (pss only) .. [string] MGF hash function name (DEFAULT: the $hash_name value)
```

### verify\_hash

Returns `1` if the signature is valid, `0` otherwise.

```
 my $pk = Crypt::PK::RSA->new($pub_key_filename);
 my $valid = $pk->verify_hash($signature, $message_hash);
 #or
 my $valid = $pk->verify_hash($signature, $message_hash, $hash_name);
 #or
 my $valid = $pk->verify_hash($signature, $message_hash, $hash_name, $padding);
 #or
 my $valid = $pk->verify_hash($signature, $message_hash, $hash_name, 'pss', $saltlen);
 #or
 my $valid = $pk->verify_hash($signature, $message_hash, $hash_name, 'pss', $saltlen, $mgf_hash_name);
 # $hash_name ................. [string] 'SHA1' (DEFAULT, INSECURE), 'SHA256' or any other hash supported by Crypt::Digest
 # $padding ................... [string] 'pss' (DEFAULT) or 'v1.5' or 'none' (INSECURE)
 # $saltlen (pss only) ........ [integer] DEFAULT is 12
 # $mgf_hash_name (pss only) .. [string] MGF hash function name (DEFAULT: the $hash_name value)
```

### is\_private

```
 my $rv = $pk->is_private;
 # 1 .. private key loaded
 # 0 .. public key loaded
 # undef .. no key loaded
```

### size

```
 my $size = $pk->size;
 # returns key size in bytes or undef if no key loaded
```

### key2hash

Returns a hashref with the key components, or `"undef"` if no key is loaded.

```
 my $hash = $pk->key2hash;
 # returns hash like this (or undef if no key loaded):
 {
   type => 1,   # integer: 1 .. private, 0 .. public
   size => 256, # integer: key size in bytes
   # all the rest are hex strings
   e  => "10001", #public exponent
   d  => "9ED5C3D3F866E06957CA0E9478A273C39BBDA4EEAC5B...", #private exponent
   N  => "D0A5CCCAE03DF9C2F5C4C8C0CE840D62CDE279990DC6...", #modulus
   p  => "D3EF0028FFAB508E2773C659E428A80FB0E9211346B4...", #p factor of N
   q  => "FC07E46B163CAB6A83B8E467D169534B2077DCDEECAE...", #q factor of N
   qP => "88C6D406F833DF73C8B734548E0385261AD51F4187CF...", #1/q mod p CRT param
   dP => "486F142FEF0A1F53269AC43D2EE4D263E2841B60DA36...", #d mod (p - 1) CRT param
   dQ => "4597284B2968B72C4212DB7E8F24360B987B80514DA9...", #d mod (q - 1) CRT param
 }
```

## OpenSSL interoperability

```
 ### let's have:
 # RSA private key in PEM format - rsakey.priv.pem
 # RSA public key in PEM format  - rsakey.pub.pem
 # data file to be signed or encrypted - input.data
```

### Encrypt by OpenSSL, decrypt by Crypt::PK::RSA

Create encrypted file (from commandline):

```
 openssl rsautl -encrypt -inkey rsakey.pub.pem -pubin -out input.encrypted.rsa -in input.data
```

Decrypt file (Perl code):

```
  use Crypt::PK::RSA;
  use Crypt::Misc 'read_rawfile';
  my $pkrsa = Crypt::PK::RSA->new("rsakey.priv.pem");
  my $encfile = read_rawfile("input.encrypted.rsa");
  my $plaintext = $pkrsa->decrypt($encfile, 'v1.5');
  print $plaintext;
```

### Encrypt by Crypt::PK::RSA, decrypt by OpenSSL

Create encrypted file (Perl code):

```
  use Crypt::PK::RSA;
  use Crypt::Misc 'write_rawfile';
  my $plaintext = 'secret message';
  my $pkrsa = Crypt::PK::RSA->new("rsakey.pub.pem");
  my $encrypted = $pkrsa->encrypt($plaintext, 'v1.5');
  write_rawfile("input.encrypted.rsa", $encrypted);
```

Decrypt file (from commandline):

```
 openssl rsautl -decrypt -inkey rsakey.priv.pem -in input.encrypted.rsa
```

### Sign by OpenSSL, verify by Crypt::PK::RSA

Create signature (from commandline):

```
 openssl dgst -sha256 -sign rsakey.priv.pem -out input.sha256-rsa.sig input.data
```

Verify signature (Perl code):

```
 use Crypt::PK::RSA;
 use Crypt::Digest 'digest_file';
 use Crypt::Misc 'read_rawfile';
 my $pkrsa = Crypt::PK::RSA->new("rsakey.pub.pem");
 my $signature = read_rawfile("input.sha256-rsa.sig");
 my $valid = $pkrsa->verify_hash($signature, digest_file("SHA256", "input.data"), "SHA256", "v1.5");
 print $valid ? "SUCCESS" : "FAILURE";
```

### Sign by Crypt::PK::RSA, verify by OpenSSL

Create signature (Perl code):

```
 use Crypt::PK::RSA;
 use Crypt::Digest 'digest_file';
 use Crypt::Misc 'write_rawfile';
 my $pkrsa = Crypt::PK::RSA->new("rsakey.priv.pem");
 my $signature = $pkrsa->sign_hash(digest_file("SHA256", "input.data"), "SHA256", "v1.5");
 write_rawfile("input.sha256-rsa.sig", $signature);
```

Verify signature (from commandline):

```
 openssl dgst -sha256 -verify rsakey.pub.pem -signature input.sha256-rsa.sig input.data
```

### Keys generated by Crypt::PK::RSA

Generate keys (Perl code):

```
 use Crypt::PK::RSA;
 use Crypt::Misc 'write_rawfile';
 my $pkrsa = Crypt::PK::RSA->new;
 $pkrsa->generate_key(256, 65537);
 write_rawfile("rsakey.pub.der",  $pkrsa->export_key_der('public'));
 write_rawfile("rsakey.priv.der", $pkrsa->export_key_der('private'));
 write_rawfile("rsakey.pub.pem",  $pkrsa->export_key_pem('public_x509'));
 write_rawfile("rsakey.priv.pem", $pkrsa->export_key_pem('private'));
 write_rawfile("rsakey-passwd.priv.pem", $pkrsa->export_key_pem('private', 'secret'));
```

Use keys by OpenSSL:

```
 openssl rsa -in rsakey.priv.der -text -inform der
 openssl rsa -in rsakey.priv.pem -text
 openssl rsa -in rsakey-passwd.priv.pem -text -inform pem -passin pass:secret
 openssl rsa -in rsakey.pub.der -pubin -text -inform der
 openssl rsa -in rsakey.pub.pem -pubin -text
```

### Keys generated by OpenSSL

Generate keys:

```
 openssl genrsa -out rsakey.priv.pem 1024
 openssl rsa -in rsakey.priv.pem -out rsakey.priv.der -outform der
 openssl rsa -in rsakey.priv.pem -out rsakey.pub.pem -pubout
 openssl rsa -in rsakey.priv.pem -out rsakey.pub.der -outform der -pubout
 openssl rsa -in rsakey.priv.pem -passout pass:secret -des3 -out rsakey-passwd.priv.pem
```

Load keys (Perl code):

```
 use Crypt::PK::RSA;
 my $pkrsa = Crypt::PK::RSA->new;
 $pkrsa->import_key("rsakey.pub.der");
 $pkrsa->import_key("rsakey.priv.der");
 $pkrsa->import_key("rsakey.pub.pem");
 $pkrsa->import_key("rsakey.priv.pem");
 $pkrsa->import_key("rsakey-passwd.priv.pem", "secret");
```

## SEE ALSO

- •

  \<https://en.wikipedia.org/wiki/RSA\_%28algorithm%29\>