如何将 DER 文件转换为 PEM 文件？

Question

I have a public key DER file and i wish to concert it to a PEM file but getting errors and Google isn't helping

Any ideas please?

alan@WW031779:/mnt/c/Users/alan/Downloads/RsaCtfTool$ openssl x509 -inform der -in pubkey.der -out certificate.pem
unable to load certificate
140024363618944:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140024363618944:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=X509
alan@WW031779:/mnt/c/Users/alan/Downloads/RsaCtfTool$ openssl x509 -in pubkey.der -inform DER -out private.pem -outform PEM
unable to load certificate
140228465136256:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140228465136256:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=X509

Even something simple like

openssl x509 -in pubkey.der -out cert.pem

Gives me

unable to load certificate
139881925907072:error:0909006C:PEM routines:get_name:no start line:../crypto/pem/pem_lib.c:745:Expecting: TRUSTED CERTIFICATE

I tried to use pkey as per a suggestion below but get

139641461281408:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
139641461281408:error:0D08303A:asn1 encoding routines:asn1_template_noexp_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:572:
139641461281408:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
139641461281408:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=RSAPrivateKey
139641461281408:error:04093004:rsa routines:old_rsa_priv_decode:RSA lib:../crypto/rsa/rsa_ameth.c:133:
139641461281408:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
139641461281408:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=PKCS8_PRIV_KEY_INFO

Also rsa

alan@WW031779:/mnt/c/Users/alan/Downloads/RsaCtfTool$ openssl rsa -inform der -in pubkey.der -out certificate.pem
unable to load Private Key
140404504073536:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140404504073536:error:0D08303A:asn1 encoding routines:asn1_template_noexp_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:572:
140404504073536:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140404504073536:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=RSAPrivateKey
140404504073536:error:04093004:rsa routines:old_rsa_priv_decode:RSA lib:../crypto/rsa/rsa_ameth.c:133:
140404504073536:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140404504073536:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=PKCS8_PRIV_KEY_INFO
alan@WW031779:/mnt/c/Users/alan/Downloads/RsaCtfTool$ openssl rsa -in pubkey.der -out cert.pem
unable to load Private Key
140227099890304:error:0909006C:PEM routines:get_name:no start line:../crypto/pem/pem_lib.c:745:Expecting: ANY PRIVATE KEY
alan@WW031779:/mnt/c/Users/alan/Downloads/RsaCtfTool$ openssl rsa -in pubkey.der -inform DER -out private.pem -outform PEM
unable to load Private Key
140152776102528:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140152776102528:error:0D08303A:asn1 encoding routines:asn1_template_noexp_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:572:
140152776102528:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140152776102528:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=RSAPrivateKey
140152776102528:error:04093004:rsa routines:old_rsa_priv_decode:RSA lib:../crypto/rsa/rsa_ameth.c:133:
140152776102528:error:0D0680A8:asn1 encoding routines:asn1_check_tlen:wrong tag:../crypto/asn1/tasn_dec.c:1149:
140152776102528:error:0D07803A:asn1 encoding routines:asn1_item_embed_d2i:nested asn1 error:../crypto/asn1/tasn_dec.c:309:Type=PKCS8_PRIV_KEY_INFO

Content of my DER file is here https://ghostbin.com/nrsmD and a snippet below

Answer 1

After several attempts to convert the DER into PEM the OP provided the DER file in question. Base64 encoded it looks like this:

BEGINPUBLICKEYMIIB...AwENDPUBLICKEY

The BEGINPUBLICKEY at the beginning and ENDPUBLICKEY look very fishy. Obviously someone took the PEM formatted public key and simply converted it from base64, then claimed that this is DER formatted. Only it is not, since the leading -----BEGIN PUBLIC KEY----- and final -----END PUBLIC KEY----- are not supposed to be included when decoding from base64, only the part between these should be decoded to get to the DER.

After repairing the base64 encoding by removing the wrong BEGINPUBLICKEY and ENDPUBLICKEY and then properly padding the remaining base64 with == decoding successfully lead to a proper DER file.

$  openssl base64 -d -in pubkey.b64 -out pubkey.der

This then could be transformed to proper PEM

$  openssl pkey -pubin -inform der -in pubkey.der -out pubkey.pem