diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index e963f49..d4aed67 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -12,6 +12,7 @@
 
 ## Tools
 OPENSSL ?= openssl
+MBEDTLS_CERT_WRITE ?= $(PWD)/../../programs/x509/cert_write
 
 ## Build the generated test data. Note that since the final outputs
 ## are committed to the repository, this target should do nothing on a
@@ -30,6 +31,7 @@
 #### Generate certificates from existing keys
 ################################################################
 
+test_ca_crt = test-ca.crt
 test_ca_key_file_rsa = test-ca.key
 test_ca_pwd_rsa = PolarSSLTest
 test_ca_config_file = test-ca.opensslconf
@@ -64,6 +66,8 @@
 	$(OPENSSL) x509 -req -extfile $(cli_crt_extensions_file) -extensions cli-rsa -CA test-ca-sha256.crt -CAkey $(test_ca_key_file_rsa) -passin "pass:$(test_ca_pwd_rsa)" -set_serial 4 -days 3653 -sha256 -in server2-rsa.csr -out $@
 all_final += server2-sha256.crt
 
+
+
 ################################################################
 #### Generate various RSA keys
 ################################################################
@@ -309,6 +313,85 @@
 ### Generate all RSA keys
 keys_rsa_all: keys_rsa_unenc keys_rsa_enc_basic keys_rsa_enc_pkcs8_v1 keys_rsa_enc_pkcs8_v2
 
+
+
+################################################################
+### Generate certificates for CRT write check tests
+################################################################
+
+### The test files use the Mbed TLS generated certificates server1*.crt,
+### but for comparison with OpenSSL also rules for OpenSSL-generated
+### certificates server1*.crt.openssl are offered.
+###
+### Known differences:
+### * OpenSSL encodes trailing zero-bits in bit-strings occurring in X.509 extension
+###   as unused bits, while Mbed TLS doesn't.
+
+test_ca_server1_db = test-ca.server1.db
+test_ca_server1_serial = test-ca.server1.serial
+test_ca_server1_config_file = test-ca.server1.opensslconf
+
+server1.csr: server1.key server1_csr.opensslconf
+	$(OPENSSL) req -keyform PEM -key server1.key -config server1_csr.opensslconf -out $@ -new
+all_final += server1.csr
+
+server1.crt: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.csr issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20110212144406 not_after=20210212144406 md=SHA1 version=3 output_file=$@
+server1.noauthid.crt: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.csr issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20110212144406 not_after=20210212144406 md=SHA1 authority_identifier=0 version=3 output_file=$@
+server1.der: server1.crt
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+all_final += server1.crt server1.noauthid.crt server1.der
+
+server1.key_usage.crt: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.csr issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20110212144406 not_after=20210212144406 md=SHA1 key_usage=digital_signature,non_repudiation,key_encipherment version=3 output_file=$@
+server1.key_usage_noauthid.crt: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.csr issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20110212144406 not_after=20210212144406 md=SHA1 key_usage=digital_signature,non_repudiation,key_encipherment authority_identifier=0 version=3 output_file=$@
+server1.key_usage.der: server1.key_usage.crt
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+all_final += server1.key_usage.crt server1.key_usage_noauthid.crt server1.key_usage.der
+
+server1.cert_type.crt: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.csr issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20110212144406 not_after=20210212144406 md=SHA1 ns_cert_type=ssl_server version=3 output_file=$@
+server1.cert_type_noauthid.crt: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.csr issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20110212144406 not_after=20210212144406 md=SHA1 ns_cert_type=ssl_server authority_identifier=0 version=3 output_file=$@
+server1.cert_type.der: server1.cert_type.crt
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+all_final += server1.cert_type.crt server1.cert_type_noauthid.crt server1.cert_type.der
+
+server1.v1.crt: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa)
+	$(MBEDTLS_CERT_WRITE) request_file=server1.csr issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) version=1 not_before=20110212144406 not_after=20210212144406 md=SHA1 version=1 output_file=$@
+server1.v1.der: server1.v1.crt
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+all_final += server1.v1.crt server1.v1.der
+
+# OpenSSL-generated certificates for comparison
+# Also provide certificates in DER format to allow
+# direct binary comparison using e.g. dumpasn1
+server1.crt.openssl server1.key_usage.crt.openssl server1.cert_type.crt.openssl: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa) $(test_ca_server1_config_file)
+	echo "01" > $(test_ca_server1_serial)
+	rm -f $(test_ca_server1_db)
+	touch $(test_ca_server1_db)
+	$(OPENSSL) ca -batch -passin "pass:$(test_ca_pwd_rsa)" -config $(test_ca_server1_config_file) -in server1.csr -extensions v3_ext -extfile $@.v3_ext -out $@
+server1.der.openssl: server1.crt.openssl
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+server1.key_usage.der.openssl: server1.key_usage.crt.openssl
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+server1.cert_type.der.openssl: server1.cert_type.crt.openssl
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+
+server1.v1.crt.openssl: server1.key server1.csr $(test_ca_crt) $(test_ca_key_file_rsa) $(test_ca_server1_config_file)
+	echo "01" > $(test_ca_server1_serial)
+	rm -f $(test_ca_server1_db)
+	touch $(test_ca_server1_db)
+	$(OPENSSL) ca -batch -passin "pass:$(test_ca_pwd_rsa)" -config $(test_ca_server1_config_file) -in server1.csr -out $@
+server1.v1.der.openssl: server1.v1.crt.openssl
+	$(OPENSSL) x509 -inform PEM -in $< -outform DER -out $@
+
+server1_all: server1.csr server1.crt server1.noauthid.crt server1.crt.openssl server1.v1.crt server1.v1.crt.openssl server1.key_usage.crt server1.key_usage_noauthid.crt server1.key_usage.crt.openssl server1.cert_type.crt server1.cert_type_noauthid.crt server1.cert_type.crt.openssl server1.der server1.der.openssl server1.v1.der server1.v1.der.openssl server1.key_usage.der server1.key_usage.der.openssl server1.cert_type.der server1.cert_type.der.openssl
+
+
+
 ################################################################
 #### Meta targets
 ################################################################
@@ -316,10 +399,15 @@
 all_final: $(all_final)
 all: $(all_intermediate) $(all_final)
 
-.PHONY: default all_final all keys_rsa_unenc keys_rsa_enc_basic keys_rsa_enc_pkcs8_v1 keys_rsa_enc_pkcs8_v2 keys_rsa_all \
-	keys_rsa_enc_basic_1024 keys_rsa_enc_basic_2048 keys_rsa_enc_basic_4096 keys_rsa_enc_pkcs8_v1_1024		 \
-	keys_rsa_enc_pkcs8_v1_2048 keys_rsa_enc_pkcs8_v1_4096 keys_rsa_enc_pkcs8_v2_1024				 \
-	keys_rsa_enc_pkcs8_v2_2048 keys_rsa_enc_pkcs8_v2_4096
+.PHONY: default all_final all
+.PHONY: keys_rsa_all
+.PHONY: keys_rsa_unenc keys_rsa_enc_basic
+.PHONY: keys_rsa_enc_pkcs8_v1 keys_rsa_enc_pkcs8_v2
+.PHONY: keys_rsa_enc_basic_1024 keys_rsa_enc_basic_2048 keys_rsa_enc_basic_4096
+.PHONY: keys_rsa_enc_pkcs8_v1_1024 keys_rsa_enc_pkcs8_v2_1024
+.PHONY: keys_rsa_enc_pkcs8_v1_2048 keys_rsa_enc_pkcs8_v2_2048
+.PHONY: keys_rsa_enc_pkcs8_v1_4096 keys_rsa_enc_pkcs8_v2_4096
+.PHONY: server1_all
 
 # These files should not be committed to the repository.
 list_intermediate:
diff --git a/tests/data_files/server1.cert_type.crt.openssl.v3_ext b/tests/data_files/server1.cert_type.crt.openssl.v3_ext
new file mode 100644
index 0000000..bd225ff
--- /dev/null
+++ b/tests/data_files/server1.cert_type.crt.openssl.v3_ext
@@ -0,0 +1,5 @@
+[v3_ext]
+basicConstraints = CA:false
+subjectKeyIdentifier=hash
+authorityKeyIdentifier=keyid
+nsCertType=server
diff --git a/tests/data_files/server1.cert_type_noauthid.crt b/tests/data_files/server1.cert_type_noauthid.crt
new file mode 100644
index 0000000..ed8b80b
--- /dev/null
+++ b/tests/data_files/server1.cert_type_noauthid.crt
@@ -0,0 +1,20 @@
+-----BEGIN CERTIFICATE-----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+bp7OvViJ4lNZnm5akmXiiD8MlBmj3eXonZUT7Snbq3AS3FrKaxerUoJUsQIDAQAB
+oz8wPTAJBgNVHRMEAjAAMB0GA1UdDgQWBBQfdNY/KcF0dEU7BRIsPai9Q1kCpjAR
+BglghkgBhvhCAQEEBAMCAEAwDQYJKoZIhvcNAQEFBQADggEBABNT+r+6vvlpjtyz
+mewrGOKPt5iwb8w2aReJ0AWuyQzTiduN26MhXq93cXHV0pHj2rD7MfiBEwBSWnf9
+FcxkE0g77GVyM9Vs9Uy/MspIqOce7JD0c36G4EI8lYce2TYwQLE9CGNl+LDxqkLy
+prijXBl/FaD+IO/SNMr3VVnfFEZqPUxg+BSTaGgD+52Z7B4nPP0xGPjlW367RGDv
+9dIkr1thve2WOeC9ixxl9K/864I7/0GdbgKSf77xl3/5vnQUOY7kugRvkvxWIgHS
+HNVnmEN2I2Nb0M8lQNF1sFDbpFwVbh9CkBF5LJNesy0VWd67Ho6EntPEb7vBFF/x
+jz0b2l4=
+-----END CERTIFICATE-----
diff --git a/tests/data_files/server1.crt.openssl.v3_ext b/tests/data_files/server1.crt.openssl.v3_ext
new file mode 100644
index 0000000..239d56a
--- /dev/null
+++ b/tests/data_files/server1.crt.openssl.v3_ext
@@ -0,0 +1,4 @@
+[v3_ext]
+basicConstraints = CA:false
+subjectKeyIdentifier=hash
+authorityKeyIdentifier=keyid
diff --git a/tests/data_files/server1.csr b/tests/data_files/server1.csr
new file mode 100644
index 0000000..804c4a5
--- /dev/null
+++ b/tests/data_files/server1.csr
@@ -0,0 +1,16 @@
+-----BEGIN CERTIFICATE REQUEST-----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+-----END CERTIFICATE REQUEST-----
diff --git a/tests/data_files/server1.key_usage.crt.openssl.v3_ext b/tests/data_files/server1.key_usage.crt.openssl.v3_ext
new file mode 100644
index 0000000..e255027
--- /dev/null
+++ b/tests/data_files/server1.key_usage.crt.openssl.v3_ext
@@ -0,0 +1,5 @@
+[v3_ext]
+basicConstraints = CA:false
+subjectKeyIdentifier=hash
+authorityKeyIdentifier=keyid
+keyUsage=critical, digitalSignature, nonRepudiation, keyEncipherment
diff --git a/tests/data_files/server1.key_usage_noauthid.crt b/tests/data_files/server1.key_usage_noauthid.crt
new file mode 100644
index 0000000..d66e515
--- /dev/null
+++ b/tests/data_files/server1.key_usage_noauthid.crt
@@ -0,0 +1,20 @@
+-----BEGIN CERTIFICATE-----
+MIIDLjCCAhagAwIBAgIBATANBgkqhkiG9w0BAQUFADA7MQswCQYDVQQGEwJOTDER
+MA8GA1UEChMIUG9sYXJTU0wxGTAXBgNVBAMTEFBvbGFyU1NMIFRlc3QgQ0EwHhcN
+MTEwMjEyMTQ0NDA2WhcNMjEwMjEyMTQ0NDA2WjA8MQswCQYDVQQGEwJOTDERMA8G
+A1UEChMIUG9sYXJTU0wxGjAYBgNVBAMTEVBvbGFyU1NMIFNlcnZlciAxMIIBIjAN
+BgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqQIfPUBq1VVTi/027oJlLhVhXom/
+uOhFkNvuiBZS0/FDUEeWEllkh2v9K+BG+XO+3c+S4ZFb7Wagb4kpeUWA0INq1UFD
+d185fAkER4KwVzlw7aPsFRkeqDMIR8EFQqn9TMO0390GH00QUUBncxMPQPhtgSVf
+CrFTxjB+FTms+Vruf5KepgVb5xOXhbUjktnUJAbVCSWJdQfdphqPPwkZvq1lLGTr
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+bp7OvViJ4lNZnm5akmXiiD8MlBmj3eXonZUT7Snbq3AS3FrKaxerUoJUsQIDAQAB
+ozwwOjAJBgNVHRMEAjAAMB0GA1UdDgQWBBQfdNY/KcF0dEU7BRIsPai9Q1kCpjAO
+BgNVHQ8BAf8EBAMCAeAwDQYJKoZIhvcNAQEFBQADggEBAJZRIISo4+rDvHXXaS43
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+3BwQet0l36FIBIJtFhcrTGlaCFUo/5bZJUPGgiOFB9ec/8lOszVlX8cH34UimWqg
+q2wXRGoXWPbuRnUWlJhI2bAv5ri9Mt7Rs4nK4wyS1ZjC8ByXMn4tk3yMjkUEqu0o
+37zoQiF+FJApu0eTKK5goA2hisyfCX9eJMppAbcyvJwoj/AmiBkXW8J3kEMJtLmZ
+VoxXYknnXumxBLxUrGuamR/3cmbaJHIHE1Dqox7hB+9miyp4lue1/uXHCocGAIeF
+JTo=
+-----END CERTIFICATE-----
diff --git a/tests/data_files/server1.noauthid.crt b/tests/data_files/server1.noauthid.crt
new file mode 100644
index 0000000..99c004f
--- /dev/null
+++ b/tests/data_files/server1.noauthid.crt
@@ -0,0 +1,19 @@
+-----BEGIN CERTIFICATE-----
+MIIDHjCCAgagAwIBAgIBATANBgkqhkiG9w0BAQUFADA7MQswCQYDVQQGEwJOTDER
+MA8GA1UEChMIUG9sYXJTU0wxGTAXBgNVBAMTEFBvbGFyU1NMIFRlc3QgQ0EwHhcN
+MTEwMjEyMTQ0NDA2WhcNMjEwMjEyMTQ0NDA2WjA8MQswCQYDVQQGEwJOTDERMA8G
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+bp7OvViJ4lNZnm5akmXiiD8MlBmj3eXonZUT7Snbq3AS3FrKaxerUoJUsQIDAQAB
+oywwKjAJBgNVHRMEAjAAMB0GA1UdDgQWBBQfdNY/KcF0dEU7BRIsPai9Q1kCpjAN
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+1B20vI/bN4XPDnw58psazdoBxFL+fAk5MbTNKETNHjBsIg==
+-----END CERTIFICATE-----
diff --git a/tests/data_files/server1.v1.crt b/tests/data_files/server1.v1.crt
index 0a4b2a5..b13be43 100644
--- a/tests/data_files/server1.v1.crt
+++ b/tests/data_files/server1.v1.crt
@@ -1,18 +1,18 @@
 -----BEGIN CERTIFICATE-----
-MIIC9DCCAdygAwIBAAIBATANBgkqhkiG9w0BAQUFADA7MQswCQYDVQQGEwJOTDER
-MA8GA1UEChMIUG9sYXJTU0wxGTAXBgNVBAMTEFBvbGFyU1NMIFRlc3QgQ0EwHhcN
-MTEwMjEyMTQ0NDA2WhcNMjEwMjEyMTQ0NDA2WjA8MQswCQYDVQQGEwJOTDERMA8G
-A1UEChMIUG9sYXJTU0wxGjAYBgNVBAMTEVBvbGFyU1NMIFNlcnZlciAxMIIBIjAN
-BgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqQIfPUBq1VVTi/027oJlLhVhXom/
-uOhFkNvuiBZS0/FDUEeWEllkh2v9K+BG+XO+3c+S4ZFb7Wagb4kpeUWA0INq1UFD
-d185fAkER4KwVzlw7aPsFRkeqDMIR8EFQqn9TMO0390GH00QUUBncxMPQPhtgSVf
-CrFTxjB+FTms+Vruf5KepgVb5xOXhbUjktnUJAbVCSWJdQfdphqPPwkZvq1lLGTr
-lZvc/kFeF6babFtpzAK6FCwWJJxK3M3Q91Jnc/EtoCP9fvQxyi1wyokLBNsupk9w
-bp7OvViJ4lNZnm5akmXiiD8MlBmj3eXonZUT7Snbq3AS3FrKaxerUoJUsQIDAQAB
-owIwADANBgkqhkiG9w0BAQUFAAOCAQEAoZVuVi7bIslKgMJhejSFXiO+ICMz1fmK
-b0tPN68mRYhI/gsjRT0cmX6GUNrg+U5mcBWhMwHgyvx1CARU4YToKZxcXGNL0DPd
-Z1hF8nCrJCZBQvNuWE7s0ufw92xz5ZfuKkVxi94RYR529F6gzgl4rpX8UQVu2ym/
-9pTlHKr4MKi9LNppyJMS89uRcb2FJFMdhAKbhNtbIjI9qGZ7x//0belAaWhq389u
-6XWFnZt35PU6Zz6YbAQ5pjZYsTaohuufgrpOlFPUuc4uR+RfGHIQ6id12lZaQC2m
-OFIBDcU0x1cFfPfMgVdBLf6klPt/v/tD77mwx0eztSp28NIf+ACw8A==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 -----END CERTIFICATE-----
diff --git a/tests/data_files/server1_csr.opensslconf b/tests/data_files/server1_csr.opensslconf
new file mode 100644
index 0000000..6e7075e
--- /dev/null
+++ b/tests/data_files/server1_csr.opensslconf
@@ -0,0 +1,10 @@
+[ req ]
+distinguished_name = req_distinguished_name
+prompt             = no
+# Restrict to non-UTF8 PrintableStrings.
+string_mask        = nombstr
+
+[ req_distinguished_name ]
+C  = NL
+O  = PolarSSL
+CN = PolarSSL Server 1
diff --git a/tests/data_files/test-ca.server1.opensslconf b/tests/data_files/test-ca.server1.opensslconf
new file mode 100644
index 0000000..4a5072e
--- /dev/null
+++ b/tests/data_files/test-ca.server1.opensslconf
@@ -0,0 +1,18 @@
+ [ ca ]
+ default_ca             = test-ca
+ 
+ [ test-ca ]
+ certificate            = test-ca.crt
+ private_key            = test-ca.key
+ serial                 = test-ca.server1.serial
+ default_md             = sha1
+ default_startdate      = 110212144406Z
+ default_enddate        = 210212144406Z
+ new_certs_dir          = ./
+ database               = ./test-ca.server1.db
+ policy                 = policy_match
+
+ [policy_match]
+ countryName            = supplied
+ organizationName       = supplied
+ commonName             = supplied
diff --git a/tests/suites/test_suite_x509write.data b/tests/suites/test_suite_x509write.data
index d4d2a98..5b54d85 100644
--- a/tests/suites/test_suite_x509write.data
+++ b/tests/suites/test_suite_x509write.data
@@ -44,19 +44,35 @@
 
 Certificate write check Server1 SHA1
 depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
-x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:0:-1:"data_files/server1.crt"
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:0:1:-1:"data_files/server1.crt":0
 
 Certificate write check Server1 SHA1, key_usage
 depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
-x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:MBEDTLS_X509_KU_DIGITAL_SIGNATURE | MBEDTLS_X509_KU_NON_REPUDIATION | MBEDTLS_X509_KU_KEY_ENCIPHERMENT:0:-1:"data_files/server1.key_usage.crt"
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:MBEDTLS_X509_KU_DIGITAL_SIGNATURE | MBEDTLS_X509_KU_NON_REPUDIATION | MBEDTLS_X509_KU_KEY_ENCIPHERMENT:0:1:-1:"data_files/server1.key_usage.crt":0
 
 Certificate write check Server1 SHA1, ns_cert_type
 depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
-x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER:-1:"data_files/server1.cert_type.crt"
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER:1:-1:"data_files/server1.cert_type.crt":0
 
 Certificate write check Server1 SHA1, version 1
 depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
-x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:0:MBEDTLS_X509_CRT_VERSION_1:"data_files/server1.v1.crt"
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:0:1:MBEDTLS_X509_CRT_VERSION_1:"data_files/server1.v1.crt":0
+
+Certificate write check Server1 SHA1, RSA_ALT
+depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:0:0:-1:"data_files/server1.noauthid.crt":1
+
+Certificate write check Server1 SHA1, RSA_ALT, key_usage
+depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:MBEDTLS_X509_KU_DIGITAL_SIGNATURE | MBEDTLS_X509_KU_NON_REPUDIATION | MBEDTLS_X509_KU_KEY_ENCIPHERMENT:0:0:-1:"data_files/server1.key_usage_noauthid.crt":1
+
+Certificate write check Server1 SHA1, RSA_ALT, ns_cert_type
+depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER:0:-1:"data_files/server1.cert_type_noauthid.crt":1
+
+Certificate write check Server1 SHA1, RSA_ALT, version 1
+depends_on:MBEDTLS_SHA1_C:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_DES_C:MBEDTLS_CIPHER_MODE_CBC:MBEDTLS_MD5_C
+x509_crt_check:"data_files/server1.key":"":"C=NL,O=PolarSSL,CN=PolarSSL Server 1":"data_files/test-ca.key":"PolarSSLTest":"C=NL,O=PolarSSL,CN=PolarSSL Test CA":"1":"20110212144406":"20210212144406":MBEDTLS_MD_SHA1:0:0:0:MBEDTLS_X509_CRT_VERSION_1:"data_files/server1.v1.crt":1
 
 X509 String to Names #1
 mbedtls_x509_string_to_names:"C=NL,O=Offspark\, Inc., OU=PolarSSL":"C=NL, O=Offspark, Inc., OU=PolarSSL":0
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index 5120837..6a66b2f 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -3,6 +3,30 @@
 #include "mbedtls/x509_csr.h"
 #include "mbedtls/pem.h"
 #include "mbedtls/oid.h"
+#include "mbedtls/rsa.h"
+
+#if defined(MBEDTLS_RSA_C)
+int mbedtls_rsa_decrypt_func( void *ctx, int mode, size_t *olen,
+                       const unsigned char *input, unsigned char *output,
+                       size_t output_max_len )
+{
+    return( mbedtls_rsa_pkcs1_decrypt( (mbedtls_rsa_context *) ctx, NULL, NULL, mode, olen,
+                               input, output, output_max_len ) );
+}
+int mbedtls_rsa_sign_func( void *ctx,
+                   int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
+                   int mode, mbedtls_md_type_t md_alg, unsigned int hashlen,
+                   const unsigned char *hash, unsigned char *sig )
+{
+    return( mbedtls_rsa_pkcs1_sign( (mbedtls_rsa_context *) ctx, f_rng, p_rng, mode,
+                            md_alg, hashlen, hash, sig ) );
+}
+size_t mbedtls_rsa_key_len_func( void *ctx )
+{
+    return( ((const mbedtls_rsa_context *) ctx)->len );
+}
+#endif /* MBEDTLS_RSA_C */
+
 /* END_HEADER */
 
 /* BEGIN_DEPENDENCIES
@@ -38,7 +62,7 @@
     if( cert_type != 0 )
         TEST_ASSERT( mbedtls_x509write_csr_set_ns_cert_type( &req, cert_type ) == 0 );
 
-    ret = mbedtls_x509write_csr_pem( &req, buf, sizeof(buf),
+    ret = mbedtls_x509write_csr_pem( &req, buf, sizeof( buf ),
                              rnd_pseudo_rand, &rnd_info );
     TEST_ASSERT( ret == 0 );
 
@@ -67,10 +91,12 @@
                      char *subject_name, char *issuer_key_file,
                      char *issuer_pwd, char *issuer_name,
                      char *serial_str, char *not_before, char *not_after,
-                     int md_type, int key_usage, int cert_type, int ver,
-                     char *cert_check_file )
+                     int md_type, int key_usage, int cert_type, int auth_ident,
+                     int ver, char *cert_check_file, int rsa_alt )
 {
-    mbedtls_pk_context subject_key, issuer_key;
+    mbedtls_pk_context subject_key, issuer_key, issuer_key_alt;
+    mbedtls_pk_context *key = &issuer_key;
+
     mbedtls_x509write_cert crt;
     unsigned char buf[4000];
     unsigned char check_buf[5000];
@@ -82,61 +108,83 @@
 
     memset( &rnd_info, 0x2a, sizeof( rnd_pseudo_info ) );
     mbedtls_mpi_init( &serial );
+
     mbedtls_pk_init( &subject_key );
-    mbedtls_pk_init( &issuer_key );
+    mbedtls_pk_init( &issuer_key  );
+    mbedtls_pk_init( &issuer_key_alt );
+
+    mbedtls_x509write_crt_init( &crt );
 
     TEST_ASSERT( mbedtls_pk_parse_keyfile( &subject_key, subject_key_file,
                                          subject_pwd ) == 0 );
+
     TEST_ASSERT( mbedtls_pk_parse_keyfile( &issuer_key, issuer_key_file,
                                          issuer_pwd ) == 0 );
+
+    /* For RSA PK contexts, create a copy as an alternative RSA context. */
+    if( rsa_alt == 1 && mbedtls_pk_get_type( &issuer_key ) == MBEDTLS_PK_RSA )
+    {
+        TEST_ASSERT( mbedtls_pk_setup_rsa_alt( &issuer_key_alt,
+                                            mbedtls_pk_rsa( issuer_key ),
+                                            mbedtls_rsa_decrypt_func,
+                                            mbedtls_rsa_sign_func,
+                                            mbedtls_rsa_key_len_func ) == 0 );
+
+        key = &issuer_key_alt;
+    }
+
     TEST_ASSERT( mbedtls_mpi_read_string( &serial, 10, serial_str ) == 0 );
 
-    mbedtls_x509write_crt_init( &crt );
     if( ver != -1 )
         mbedtls_x509write_crt_set_version( &crt, ver );
+
     TEST_ASSERT( mbedtls_x509write_crt_set_serial( &crt, &serial ) == 0 );
     TEST_ASSERT( mbedtls_x509write_crt_set_validity( &crt, not_before,
-                                                   not_after ) == 0 );
+                                                     not_after ) == 0 );
     mbedtls_x509write_crt_set_md_alg( &crt, md_type );
     TEST_ASSERT( mbedtls_x509write_crt_set_issuer_name( &crt, issuer_name ) == 0 );
     TEST_ASSERT( mbedtls_x509write_crt_set_subject_name( &crt, subject_name ) == 0 );
     mbedtls_x509write_crt_set_subject_key( &crt, &subject_key );
-    mbedtls_x509write_crt_set_issuer_key( &crt, &issuer_key );
+
+    mbedtls_x509write_crt_set_issuer_key( &crt, key );
 
     if( crt.version >= MBEDTLS_X509_CRT_VERSION_3 )
     {
         TEST_ASSERT( mbedtls_x509write_crt_set_basic_constraints( &crt, 0, 0 ) == 0 );
         TEST_ASSERT( mbedtls_x509write_crt_set_subject_key_identifier( &crt ) == 0 );
-        TEST_ASSERT( mbedtls_x509write_crt_set_authority_key_identifier( &crt ) == 0 );
+        if( auth_ident )
+            TEST_ASSERT( mbedtls_x509write_crt_set_authority_key_identifier( &crt ) == 0 );
         if( key_usage != 0 )
             TEST_ASSERT( mbedtls_x509write_crt_set_key_usage( &crt, key_usage ) == 0 );
         if( cert_type != 0 )
             TEST_ASSERT( mbedtls_x509write_crt_set_ns_cert_type( &crt, cert_type ) == 0 );
     }
 
-    ret = mbedtls_x509write_crt_pem( &crt, buf, sizeof(buf),
-                             rnd_pseudo_rand, &rnd_info );
+    ret = mbedtls_x509write_crt_pem( &crt, buf, sizeof( buf ),
+                                     rnd_pseudo_rand, &rnd_info );
     TEST_ASSERT( ret == 0 );
 
     pem_len = strlen( (char *) buf );
 
     f = fopen( cert_check_file, "r" );
     TEST_ASSERT( f != NULL );
-    olen = fread( check_buf, 1, sizeof(check_buf), f );
+    olen = fread( check_buf, 1, sizeof( check_buf ), f );
     fclose( f );
-    TEST_ASSERT( olen < sizeof(check_buf) );
+    TEST_ASSERT( olen < sizeof( check_buf ) );
 
     TEST_ASSERT( olen >= pem_len - 1 );
     TEST_ASSERT( memcmp( buf, check_buf, pem_len - 1 ) == 0 );
 
     ret = mbedtls_x509write_crt_der( &crt, buf, pem_len / 2,
                             rnd_pseudo_rand, &rnd_info );
+
     TEST_ASSERT( ret == MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
 exit:
     mbedtls_x509write_crt_free( &crt );
-    mbedtls_pk_free( &issuer_key );
+    mbedtls_pk_free( &issuer_key_alt );
     mbedtls_pk_free( &subject_key );
+    mbedtls_pk_free( &issuer_key );
     mbedtls_mpi_free( &serial );
 }
 /* END_CASE */