class OpenSSL::PKey::RSA

Generates an RSA keypair.

See also OpenSSL::PKey.generate_key.

size

The desired key size in bits.

exponent

An odd Integer, normally 3, 17, or 65537.

Generates or loads an RSA keypair.

If called without arguments, creates a new instance with no key components set. They can be set individually by set_key, set_factors, and

set_crt_params. This form is not compatible with OpenSSL 3.0 or later.

If called with a String, tries to parse as DER or PEM encoding of an RSA key. Note that if password is not specified, but the key is encrypted with a password, OpenSSL will prompt for it. See also OpenSSL::PKey.read which can parse keys of any kind.

If called with a number, generates a new key pair. This form works as an alias of RSA.generate.

Examples: OpenSSL::PKey::RSA.new 2048 OpenSSL::PKey::RSA.new File.read ‘rsa.pem’ OpenSSL::PKey::RSA.new File.read(‘rsa.pem’), ‘my password’

Serializes a private or public key to a PEM-encoding.

When the key contains public components only : Serializes it into an X.509 SubjectPublicKeyInfo. The parameters cipher and password are ignored.

A PEM-encoded key will look like:

    -----BEGIN PUBLIC KEY-----
    [...]
    -----END PUBLIC KEY-----

Consider using #public_to_pem instead. This serializes the key into an
X.509 SubjectPublicKeyInfo regardless of whether the key is a public key
or a private key.

When the key contains private components, and no parameters are given : Serializes it into a PKCS #1 RSAPrivateKey.

A PEM-encoded key will look like:

    -----BEGIN RSA PRIVATE KEY-----
    [...]
    -----END RSA PRIVATE KEY-----

When the key contains private components, and cipher and password are given : Serializes it into a PKCS #1 RSAPrivateKey and encrypts it in OpenSSL’s traditional PEM encryption format. cipher must be a cipher name understood by OpenSSL::Cipher.new or an instance of OpenSSL::Cipher.

An encrypted PEM-encoded key will look like:

    -----BEGIN RSA PRIVATE KEY-----
    Proc-Type: 4,ENCRYPTED
    DEK-Info: AES-128-CBC,733F5302505B34701FC41F5C0746E4C0

    [...]
    -----END RSA PRIVATE KEY-----

Note that this format uses MD5 to derive the encryption key, and hence
will not be available on FIPS-compliant systems.

<strong>This method is kept for compatibility.</strong> This should only be used when the PKCS #1 RSAPrivateKey format is required.

Consider using public_to_pem (X.509 SubjectPublicKeyInfo) or private_to_pem (PKCS #8 PrivateKeyInfo or EncryptedPrivateKeyInfo) instead.

Stores all parameters of key to a Hash.

The hash has keys ‘n’, ‘e’, ‘d’, ‘p’, ‘q’, ‘dmp1’, ‘dmq1’, and ‘iqmp’.

Does this keypair contain a private key?

Decrypt string, which has been encrypted with the public key, with the private key. padding defaults to PKCS1_PADDING, which is known to be insecure but is kept for backwards compatibility.

<strong>Deprecated in version 3.0</strong>. Consider using PKey::PKey#encrypt and PKey::PKey#decrypt instead.

Encrypt string with the private key. padding defaults to PKCS1_PADDING, which is known to be insecure but is kept for backwards compatibility. The encrypted string output can be decrypted using public_decrypt.

<strong>Deprecated in version 3.0</strong>. Consider using PKey::PKey#sign_raw and PKey::PKey#verify_raw, and PKey::PKey#verify_recover instead.

The return value is always true since every private key is also a public key.

Decrypt string, which has been encrypted with the private key, with the public key. padding defaults to PKCS1_PADDING which is known to be insecure but is kept for backwards compatibility.

<strong>Deprecated in version 3.0</strong>. Consider using PKey::PKey#sign_raw and PKey::PKey#verify_raw, and PKey::PKey#verify_recover instead.

Encrypt string with the public key. padding defaults to PKCS1_PADDING, which is known to be insecure but is kept for backwards compatibility. The encrypted string output can be decrypted using private_decrypt.

<strong>Deprecated in version 3.0</strong>. Consider using PKey::PKey#encrypt and PKey::PKey#decrypt instead.

Returns a new RSA instance that carries just the public key components.

This method is provided for backwards compatibility. In most cases, there is no need to call this method.

For the purpose of serializing the public key, to PEM or DER encoding of X.509 SubjectPublicKeyInfo format, check PKey#public_to_pem and PKey#public_to_der.

Sets dmp1, dmq1, iqmp for the RSA instance. They are calculated by d mod (p - 1), d mod (q - 1) and q^(-1) mod p respectively.

Sets p, q for the RSA instance.

Sets n, e, d for the RSA instance.

Signs data using the Probabilistic Signature Scheme (RSA-PSS) and returns the calculated signature.

PKeyError will be raised if an error occurs.

See verify_pss for the verification operation.

Parameters

digest

A String containing the message digest algorithm name.

data

A String. The data to be signed.

salt_length

The length in octets of the salt. Two special values are reserved: :digest means the digest length, and :max means the maximum possible length for the combination of the private key and the selected message digest algorithm.

mgf1_hash

The hash algorithm used in MGF1 (the currently supported mask generation function (MGF)).

Example

data = "Sign me!"
pkey = OpenSSL::PKey::RSA.new(2048)
signature = pkey.sign_pss("SHA256", data, salt_length: :max, mgf1_hash: "SHA256")
pub_key = OpenSSL::PKey.read(pkey.public_to_der)
puts pub_key.verify_pss("SHA256", signature, data,
                        salt_length: :auto, mgf1_hash: "SHA256") # => true

Serializes a private or public key to a DER-encoding.

See to_pem for details.

<strong>This method is kept for compatibility.</strong> This should only be used when the PKCS #1 RSAPrivateKey format is required.

Consider using public_to_der or private_to_der instead.

THIS METHOD IS INSECURE, PRIVATE INFORMATION CAN LEAK OUT!!!

Dumps all parameters of a keypair to a String

Don’t use :-)) (It’s up to you)

Verifies data using the Probabilistic Signature Scheme (RSA-PSS).

The return value is true if the signature is valid, false otherwise. PKeyError will be raised if an error occurs.

See sign_pss for the signing operation and an example code.

Parameters

digest

A String containing the message digest algorithm name.

data

A String. The data to be signed.

salt_length

The length in octets of the salt. Two special values are reserved: :digest means the digest length, and :auto means automatically determining the length based on the signature.

mgf1_hash

The hash algorithm used in MGF1.