diff --git a/include/gmssl/asn1.h b/include/gmssl/asn1.h
index 4a756307..212ec334 100644
--- a/include/gmssl/asn1.h
+++ b/include/gmssl/asn1.h
@@ -1,5 +1,5 @@
 /*
- *  Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
+ *  Copyright 2014-2023 The GmSSL Project. All Rights Reserved.
  *
  *  Licensed under the Apache License, Version 2.0 (the License); you may
  *  not use this file except in compliance with the License.
@@ -178,6 +178,7 @@ int asn1_utf8_string_from_der_ex(int tag, const char **d, size_t *dlen, const ui
 #define asn1_implicit_utf8_string_from_der(i,d,dlen,in,inlen) asn1_utf8_string_from_der_ex(ASN1_TAG_IMPLICIT(i),d,dlen,in,inlen)
 
 int asn1_printable_string_check(const char *d, size_t dlen);
+int asn1_printable_string_case_ignore_match(const char *a, size_t alen, const char *b, size_t blen);
 int asn1_printable_string_to_der_ex(int tag, const char *d, size_t dlen, uint8_t **out, size_t *outlen);
 int asn1_printable_string_from_der_ex(int tag, const char **d, size_t *dlen, const uint8_t **in, size_t *inlen);
 #define asn1_printable_string_to_der(d,dlen,out,outlen)	asn1_printable_string_to_der_ex(ASN1_TAG_PrintableString,d,dlen,out,outlen)
diff --git a/src/asn1.c b/src/asn1.c
index 19667607..735b73fe 100644
--- a/src/asn1.c
+++ b/src/asn1.c
@@ -1,5 +1,5 @@
 /*
- *  Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
+ *  Copyright 2014-2023 The GmSSL Project. All Rights Reserved.
  *
  *  Licensed under the Apache License, Version 2.0 (the License); you may
  *  not use this file except in compliance with the License.
@@ -118,8 +118,62 @@ int asn1_utf8_string_check(const char *a, size_t alen)
 	return 1;
 }
 
+static int asn1_char_is_printable(int a)
+{
+	if (isalpha(a) || isdigit(a)) {
+		return 1;
+	}
+	switch (a) {
+	case ' ': case '\'': case '(': case ')':
+	case '+': case ',': case '-': case '.':
+	case '/': case ':': case '=': case '?':
+		return 1;
+	}
+	return 0;
+}
+
 int asn1_printable_string_check(const char *a, size_t alen)
 {
+	size_t i;
+	for (i = 0; i < alen; i++) {
+		if (asn1_char_is_printable(a[i]) != 1) {
+			error_print();
+			return -1;
+		}
+	}
+	return 1;
+}
+
+int asn1_printable_string_case_ignore_match(const char *a, size_t alen,
+	const char *b, size_t blen)
+{
+	// remove leading and suffix space chars
+	while (alen && *a == ' ') {
+		a++;
+		alen--;
+	}
+	while (alen && a[alen - 1] == ' ') {
+		alen--;
+	}
+
+	// remove leading and suffix space chars
+	while (blen && *b == ' ') {
+		b++;
+		blen--;
+	}
+	while (blen && b[blen - 1] == ' ') {
+		blen--;
+	}
+
+	if (alen != blen) {
+		return 0;
+	}
+	// case insensitive compare
+	while (alen--) {
+		if (toupper(*a) != toupper(*b)) {
+			return 0;
+		}
+	}
 	return 1;
 }
 
diff --git a/tests/asn1test.c b/tests/asn1test.c
index 6b5b829a..a55b383f 100644
--- a/tests/asn1test.c
+++ b/tests/asn1test.c
@@ -1,5 +1,5 @@
 /*
- *  Copyright 2014-2022 The GmSSL Project. All Rights Reserved.
+ *  Copyright 2014-2023 The GmSSL Project. All Rights Reserved.
  *
  *  Licensed under the Apache License, Version 2.0 (the License); you may
  *  not use this file except in compliance with the License.
@@ -405,6 +405,58 @@ static int test_asn1_printable_string(void)
 	return 1;
 }
 
+static int test_asn1_printable_string_check(void)
+{
+	char *printable_str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 '()+,-./:=?";
+	if (asn1_printable_string_check(printable_str, strlen(printable_str)) != 1) {
+		error_print();
+		return -1;
+	}
+
+	if (asn1_printable_string_check("a*b", 3) == 1) {
+		error_print();
+		return -1;
+	}
+
+	printf("%s() ok\n", __FUNCTION__);
+	return 1;
+}
+
+static int test_asn1_printable_string_case_ignore_match(void)
+{
+	if (asn1_printable_string_case_ignore_match("HELLO", 5, "WORLD", 5) == 1) {
+		error_print();
+		return -1;
+	}
+
+	if (asn1_printable_string_case_ignore_match("HELLO", 5, "HELLO", 5) != 1) {
+		error_print();
+		return -1;
+	}
+	if (asn1_printable_string_case_ignore_match("HELLO", 5, "hello", 5) != 1) {
+		error_print();
+		return -1;
+	}
+	if (asn1_printable_string_case_ignore_match("  HELLO", 7, "hello", 5) != 1) {
+		error_print();
+		return -1;
+	}
+	if (asn1_printable_string_case_ignore_match("  HELLO", 7, "hello   ", 8) != 1) {
+		error_print();
+		return -1;
+	}
+	if (asn1_printable_string_case_ignore_match(" A2b ", 5, "  a2B  ", 7) != 1) {
+		error_print();
+		return -1;
+	}
+	if (asn1_printable_string_case_ignore_match("     ", 5, "       ", 7) != 1) {
+		error_print();
+		return -1;
+	}
+	printf("%s() ok\n", __FUNCTION__);
+	return 1;
+}
+
 static int test_asn1_utf8_string(void)
 {
 	char *tests[] = {
@@ -642,6 +694,7 @@ int main(void)
 	if (test_asn1_null() != 1) goto err;
 	if (test_asn1_object_identifier() != 1) goto err;
 	if (test_asn1_printable_string() != 1) goto err;
+	if (test_asn1_printable_string_case_ignore_match() != 1) goto err;
 	if (test_asn1_utf8_string() != 1) goto err;
 	if (test_asn1_ia5_string() != 1) goto err;
 	if (test_asn1_time() != 1) goto err;