Save RSA public keys in the pre-1.9.3 PKCS#1 format

gistfile1.txt

require 'openssl'
require 'base64'

rsa = OpenSSL::PKey::RSA.new(2048)
modulus = rsa.n
exponent = rsa.e

ary = [OpenSSL::ASN1::Integer.new(modulus), OpenSSL::ASN1::Integer.new(exponent)]
pub_key = OpenSSL::ASN1::Sequence.new(ary)
base64 = Base64.encode64(pub_key.to_der)

#This is the equivalent to the PKCS#1 encoding used before 1.9.3
pem = "-----BEGIN RSA PUBLIC KEY-----\n#{base64}-----END RSA PUBLIC KEY-----"

Hello, this is useful but i am facing this issue:

`[20] pry(#)> ary = [OpenSSL::ASN1::Integer.new(rsa_public['n']), OpenSSL::ASN1::Integer]
14:00:41 rails.1 | => [#<OpenSSL::ASN1::Integer:0x00007fd881238988
14:00:41 rails.1 | @indefinite_length=false,
14:00:41 rails.1 | @tag=2,
14:00:41 rails.1 | @tag_class=:UNIVERSAL,
14:00:41 rails.1 | @tagging=nil,
14:00:41 rails.1 | @value=
14:00:41 rails.1 | "oc7PjsJehmf7z_FCQWKbm1v8QddVDC5dZu9mM_DtmhHmuGeD5DGTUf2tAZSDG_hj6tX8FPAKP7n0dGCsDtVrKj-_x3ck9pMreAcoSaCP0YHZOArecyymSZIL6-RY4Fm-r_fF_c9JDEkftp7l_El_aui0hD400V9VkFiSCDnJYES7wSfsWmcUv7hx_wb1jrseGoIMFtA5CiRhSwaCeHHrFRVd6zkuCZ6ACp9OL0dCVOVRosKioRFH9hkyzixAdIEqRYU2YxaIPgPV2hNoLAKoXiVtYV2yB0RR6hwHeGLPijGX5B9xe4Tee5qpeXlaELG6kKaUKn5ZrH185GEMQlKQ8Q">,
14:00:41 rails.1 | #<OpenSSL::ASN1::Integer:0x00007fd881238960
14:00:41 rails.1 | @indefinite_length=false,
14:00:41 rails.1 | @tag=2,
14:00:41 rails.1 | @tag_class=:UNIVERSAL,
14:00:41 rails.1 | @tagging=nil,
14:00:41 rails.1 | @value="AQAB">]

14:01:11 rails.1 | [21] pry(#)> pub_key = OpenSSL::ASN1::Sequence.new(ary)
14:01:11 rails.1 | => #<OpenSSL::ASN1::Sequence:0x00007fd88b990988
14:01:11 rails.1 | @indefinite_length=false,
14:01:11 rails.1 | @tag=16,
14:01:11 rails.1 | @tag_class=:UNIVERSAL,
14:01:11 rails.1 | @tagging=nil,
14:01:11 rails.1 | @value=
14:01:11 rails.1 | [#<OpenSSL::ASN1::Integer:0x00007fd881238988
14:01:11 rails.1 | @indefinite_length=false,
14:01:11 rails.1 | @tag=2,
14:01:11 rails.1 | @tag_class=:UNIVERSAL,
14:01:11 rails.1 | @tagging=nil,
14:01:11 rails.1 | @value=
14:01:11 rails.1 | "oc7PjsJehmf7z_FCQWKbm1v8QddVDC5dZu9mM_DtmhHmuGeD5DGTUf2tAZSDG_hj6tX8FPAKP7n0dGCsDtVrKj-_x3ck9pMreAcoSaCP0YHZOArecyymSZIL6-RY4Fm-r_fF_c9JDEkftp7l_El_aui0hD400V9VkFiSCDnJYES7wSfsWmcUv7hx_wb1jrseGoIMFtA5CiRhSwaCeHHrFRVd6zkuCZ6ACp9OL0dCVOVRosKioRFH9hkyzixAdIEqRYU2YxaIPgPV2hNoLAKoXiVtYV2yB0RR6hwHeGLPijGX5B9xe4Tee5qpeXlaELG6kKaUKn5ZrH185GEMQlKQ8Q">,
14:01:11 rails.1 | #<OpenSSL::ASN1::Integer:0x00007fd881238960
14:01:11 rails.1 | @indefinite_length=false,
14:01:11 rails.1 | @tag=2,
14:01:11 rails.1 | @tag_class=:UNIVERSAL,
14:01:11 rails.1 | @tagging=nil,
14:01:11 rails.1 | @value="AQAB">]>

14:01:23 rails.1 | [22] pry(#)> base64 = Base64.encode64(pub_key.to_der)
14:01:23 rails.1 | TypeError: Cannot convert into OpenSSL::BN
14:01:23 rails.1 | from (pry):13:in `to_der'

Any idea how i can resolve this?
`