diff --git a/crypto/asn1/a_bitstr.c b/crypto/asn1/a_bitstr.c
index 3942638..4024ed2 100644
--- a/crypto/asn1/a_bitstr.c
+++ b/crypto/asn1/a_bitstr.c
@@ -70,7 +70,7 @@
     return M_ASN1_BIT_STRING_set(x, d, len);
 }
 
-int i2c_ASN1_BIT_STRING(ASN1_BIT_STRING *a, unsigned char **pp)
+int i2c_ASN1_BIT_STRING(const ASN1_BIT_STRING *a, unsigned char **pp)
 {
     int ret, j, bits, len;
     unsigned char *p, *d;
@@ -233,7 +233,7 @@
     return (1);
 }
 
-int ASN1_BIT_STRING_get_bit(ASN1_BIT_STRING *a, int n)
+int ASN1_BIT_STRING_get_bit(const ASN1_BIT_STRING *a, int n)
 {
     int w, v;
 
@@ -250,7 +250,7 @@
  * which is not specified in 'flags', 1 otherwise.
  * 'len' is the length of 'flags'.
  */
-int ASN1_BIT_STRING_check(ASN1_BIT_STRING *a,
+int ASN1_BIT_STRING_check(const ASN1_BIT_STRING *a,
                           unsigned char *flags, int flags_len)
 {
     int i, ok;
diff --git a/crypto/asn1/a_enum.c b/crypto/asn1/a_enum.c
index 11e60ac..b99663b 100644
--- a/crypto/asn1/a_enum.c
+++ b/crypto/asn1/a_enum.c
@@ -108,7 +108,7 @@
     return (1);
 }
 
-long ASN1_ENUMERATED_get(ASN1_ENUMERATED *a)
+long ASN1_ENUMERATED_get(const ASN1_ENUMERATED *a)
 {
     int neg = 0, i;
 
@@ -147,7 +147,7 @@
     return r;
 }
 
-ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(BIGNUM *bn, ASN1_ENUMERATED *ai)
+ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(const BIGNUM *bn, ASN1_ENUMERATED *ai)
 {
     ASN1_ENUMERATED *ret;
     int len, j;
@@ -183,7 +183,7 @@
     return (NULL);
 }
 
-BIGNUM *ASN1_ENUMERATED_to_BN(ASN1_ENUMERATED *ai, BIGNUM *bn)
+BIGNUM *ASN1_ENUMERATED_to_BN(const ASN1_ENUMERATED *ai, BIGNUM *bn)
 {
     BIGNUM *ret;
 
diff --git a/crypto/asn1/a_int.c b/crypto/asn1/a_int.c
index 7b483f2..2eda6c0 100644
--- a/crypto/asn1/a_int.c
+++ b/crypto/asn1/a_int.c
@@ -115,7 +115,7 @@
  * followed by optional zeros isn't padded.
  */
 
-int i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)
+int i2c_ASN1_INTEGER(const ASN1_INTEGER *a, unsigned char **pp)
 {
     int pad = 0, ret, i, neg;
     unsigned char *p, *n, pb = 0;
diff --git a/crypto/asn1/a_object.c b/crypto/asn1/a_object.c
index 97335bf..aa98453 100644
--- a/crypto/asn1/a_object.c
+++ b/crypto/asn1/a_object.c
@@ -66,7 +66,7 @@
 #include "../internal.h"
 
 
-int i2d_ASN1_OBJECT(ASN1_OBJECT *a, unsigned char **pp)
+int i2d_ASN1_OBJECT(const ASN1_OBJECT *a, unsigned char **pp)
 {
     unsigned char *p, *allocated = NULL;
     int objsize;
@@ -98,12 +98,12 @@
     return objsize;
 }
 
-int i2t_ASN1_OBJECT(char *buf, int buf_len, ASN1_OBJECT *a)
+int i2t_ASN1_OBJECT(char *buf, int buf_len, const ASN1_OBJECT *a)
 {
     return OBJ_obj2txt(buf, buf_len, a, 0);
 }
 
-int i2a_ASN1_OBJECT(BIO *bp, ASN1_OBJECT *a)
+int i2a_ASN1_OBJECT(BIO *bp, const ASN1_OBJECT *a)
 {
     char buf[80], *p = buf;
     int i;
diff --git a/crypto/asn1/a_time.c b/crypto/asn1/a_time.c
index 51aae5d..98a9c3e 100644
--- a/crypto/asn1/a_time.c
+++ b/crypto/asn1/a_time.c
@@ -100,7 +100,7 @@
     return ASN1_GENERALIZEDTIME_adj(s, t, offset_day, offset_sec);
 }
 
-int ASN1_TIME_check(ASN1_TIME *t)
+int ASN1_TIME_check(const ASN1_TIME *t)
 {
     if (t->type == V_ASN1_GENERALIZEDTIME)
         return ASN1_GENERALIZEDTIME_check(t);
@@ -110,7 +110,7 @@
 }
 
 /* Convert an ASN1_TIME structure to GeneralizedTime */
-ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t,
+ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(const ASN1_TIME *t,
                                                    ASN1_GENERALIZEDTIME **out)
 {
     ASN1_GENERALIZEDTIME *ret = NULL;
diff --git a/crypto/asn1/a_type.c b/crypto/asn1/a_type.c
index 734ff8b..c12edfa 100644
--- a/crypto/asn1/a_type.c
+++ b/crypto/asn1/a_type.c
@@ -61,7 +61,7 @@
 #include <openssl/mem.h>
 #include <openssl/obj.h>
 
-int ASN1_TYPE_get(ASN1_TYPE *a)
+int ASN1_TYPE_get(const ASN1_TYPE *a)
 {
     if ((a->value.ptr != NULL) || (a->type == V_ASN1_NULL))
         return (a->type);
diff --git a/crypto/asn1/asn1_lib.c b/crypto/asn1/asn1_lib.c
index 8526aba..1091009 100644
--- a/crypto/asn1/asn1_lib.c
+++ b/crypto/asn1/asn1_lib.c
@@ -430,7 +430,7 @@
     return;
 }
 
-int ASN1_STRING_type(ASN1_STRING *x)
+int ASN1_STRING_type(const ASN1_STRING *x)
 {
     return M_ASN1_STRING_type(x);
 }
diff --git a/crypto/asn1/asn1_test.cc b/crypto/asn1/asn1_test.cc
index ff80e49..7f71c8c 100644
--- a/crypto/asn1/asn1_test.cc
+++ b/crypto/asn1/asn1_test.cc
@@ -174,7 +174,7 @@
   static const uint8_t kDER[] = {0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
                                  0xf7, 0x0d, 0x01, 0x01, 0x01};
   const ASN1_OBJECT *obj = OBJ_nid2obj(NID_rsaEncryption);
-  TestSerialize(const_cast<ASN1_OBJECT *>(obj), i2d_ASN1_OBJECT, kDER);
+  TestSerialize(obj, i2d_ASN1_OBJECT, kDER);
 }
 
 TEST(ASN1Test, SerializeBoolean) {
diff --git a/crypto/asn1/asn_pack.c b/crypto/asn1/asn_pack.c
index eff54e5..3c7116e 100644
--- a/crypto/asn1/asn_pack.c
+++ b/crypto/asn1/asn_pack.c
@@ -93,7 +93,7 @@
 
 /* Extract an ASN1 object from an ASN1_STRING */
 
-void *ASN1_item_unpack(ASN1_STRING *oct, const ASN1_ITEM *it)
+void *ASN1_item_unpack(const ASN1_STRING *oct, const ASN1_ITEM *it)
 {
     const unsigned char *p;
     void *ret;
diff --git a/crypto/asn1/f_enum.c b/crypto/asn1/f_enum.c
index 7ce479d..e28755d 100644
--- a/crypto/asn1/f_enum.c
+++ b/crypto/asn1/f_enum.c
@@ -60,7 +60,7 @@
 
 /* Based on a_int.c: equivalent ENUMERATED functions */
 
-int i2a_ASN1_ENUMERATED(BIO *bp, ASN1_ENUMERATED *a)
+int i2a_ASN1_ENUMERATED(BIO *bp, const ASN1_ENUMERATED *a)
 {
     int i, n = 0;
     static const char *h = "0123456789ABCDEF";
diff --git a/crypto/asn1/f_int.c b/crypto/asn1/f_int.c
index 79ea152..25338d8 100644
--- a/crypto/asn1/f_int.c
+++ b/crypto/asn1/f_int.c
@@ -58,7 +58,7 @@
 
 #include <openssl/bio.h>
 
-int i2a_ASN1_INTEGER(BIO *bp, ASN1_INTEGER *a)
+int i2a_ASN1_INTEGER(BIO *bp, const ASN1_INTEGER *a)
 {
     int i, n = 0;
     static const char *h = "0123456789ABCDEF";
diff --git a/crypto/asn1/f_string.c b/crypto/asn1/f_string.c
index 97c6ae7..01d9dec 100644
--- a/crypto/asn1/f_string.c
+++ b/crypto/asn1/f_string.c
@@ -58,7 +58,7 @@
 
 #include <openssl/bio.h>
 
-int i2a_ASN1_STRING(BIO *bp, ASN1_STRING *a, int type)
+int i2a_ASN1_STRING(BIO *bp, const ASN1_STRING *a, int type)
 {
     int i, n = 0;
     static const char *h = "0123456789ABCDEF";
diff --git a/crypto/x509/a_strex.c b/crypto/x509/a_strex.c
index 6dc183a..eeec5d1 100644
--- a/crypto/x509/a_strex.c
+++ b/crypto/x509/a_strex.c
@@ -296,7 +296,7 @@
  */
 
 static int do_dump(unsigned long lflags, char_io *io_ch, void *arg,
-                   ASN1_STRING *str)
+                   const ASN1_STRING *str)
 {
     /*
      * Placing the ASN1_STRING in a temp ASN1_TYPE allows the DER encoding to
@@ -354,7 +354,7 @@
  */
 
 static int do_print_ex(char_io *io_ch, void *arg, unsigned long lflags,
-                       ASN1_STRING *str)
+                       const ASN1_STRING *str)
 {
     int outlen, len;
     int type;
@@ -610,13 +610,13 @@
 }
 #endif
 
-int ASN1_STRING_print_ex(BIO *out, ASN1_STRING *str, unsigned long flags)
+int ASN1_STRING_print_ex(BIO *out, const ASN1_STRING *str, unsigned long flags)
 {
     return do_print_ex(send_bio_chars, out, flags, str);
 }
 
 #ifndef OPENSSL_NO_FP_API
-int ASN1_STRING_print_ex_fp(FILE *fp, ASN1_STRING *str, unsigned long flags)
+int ASN1_STRING_print_ex_fp(FILE *fp, const ASN1_STRING *str, unsigned long flags)
 {
     return do_print_ex(send_fp_chars, fp, flags, str);
 }
diff --git a/crypto/x509/asn1_gen.c b/crypto/x509/asn1_gen.c
index 98a6fac..f61fdde 100644
--- a/crypto/x509/asn1_gen.c
+++ b/crypto/x509/asn1_gen.c
@@ -123,7 +123,7 @@
     int exp_count;
 } tag_exp_arg;
 
-static ASN1_TYPE *generate_v3(char *str, X509V3_CTX *cnf, int depth,
+static ASN1_TYPE *generate_v3(const char *str, X509V3_CTX *cnf, int depth,
                               int *perr);
 static int bitstr_cb(const char *elem, int len, void *bitstr);
 static int asn1_cb(const char *elem, int len, void *bitstr);
@@ -136,7 +136,7 @@
 static ASN1_TYPE *asn1_str2type(const char *str, int format, int utype);
 static int asn1_str2tag(const char *tagstr, int len);
 
-ASN1_TYPE *ASN1_generate_nconf(char *str, CONF *nconf)
+ASN1_TYPE *ASN1_generate_nconf(const char *str, CONF *nconf)
 {
     X509V3_CTX cnf;
 
@@ -147,7 +147,7 @@
     return ASN1_generate_v3(str, &cnf);
 }
 
-ASN1_TYPE *ASN1_generate_v3(char *str, X509V3_CTX *cnf)
+ASN1_TYPE *ASN1_generate_v3(const char *str, X509V3_CTX *cnf)
 {
     int err = 0;
     ASN1_TYPE *ret = generate_v3(str, cnf, 0, &err);
@@ -156,7 +156,7 @@
     return ret;
 }
 
-static ASN1_TYPE *generate_v3(char *str, X509V3_CTX *cnf, int depth,
+static ASN1_TYPE *generate_v3(const char *str, X509V3_CTX *cnf, int depth,
                               int *perr)
 {
     ASN1_TYPE *ret;
diff --git a/include/openssl/asn1.h b/include/openssl/asn1.h
index 6ae831b..c1a8d5a 100644
--- a/include/openssl/asn1.h
+++ b/include/openssl/asn1.h
@@ -619,14 +619,14 @@
 
 DECLARE_ASN1_FUNCTIONS_fname(ASN1_TYPE, ASN1_ANY, ASN1_TYPE)
 
-OPENSSL_EXPORT int ASN1_TYPE_get(ASN1_TYPE *a);
+OPENSSL_EXPORT int ASN1_TYPE_get(const ASN1_TYPE *a);
 OPENSSL_EXPORT void ASN1_TYPE_set(ASN1_TYPE *a, int type, void *value);
 OPENSSL_EXPORT int ASN1_TYPE_set1(ASN1_TYPE *a, int type, const void *value);
 OPENSSL_EXPORT int ASN1_TYPE_cmp(const ASN1_TYPE *a, const ASN1_TYPE *b);
 
 OPENSSL_EXPORT ASN1_OBJECT *	ASN1_OBJECT_new(void );
 OPENSSL_EXPORT void		ASN1_OBJECT_free(ASN1_OBJECT *a);
-OPENSSL_EXPORT int		i2d_ASN1_OBJECT(ASN1_OBJECT *a,unsigned char **pp);
+OPENSSL_EXPORT int		i2d_ASN1_OBJECT(const ASN1_OBJECT *a,unsigned char **pp);
 OPENSSL_EXPORT ASN1_OBJECT *	c2i_ASN1_OBJECT(ASN1_OBJECT **a,const unsigned char **pp,
 						long length);
 OPENSSL_EXPORT ASN1_OBJECT *	d2i_ASN1_OBJECT(ASN1_OBJECT **a,const unsigned char **pp,
@@ -648,23 +648,23 @@
 OPENSSL_EXPORT void		ASN1_STRING_set0(ASN1_STRING *str, void *data, int len);
 OPENSSL_EXPORT int ASN1_STRING_length(const ASN1_STRING *x);
 OPENSSL_EXPORT void ASN1_STRING_length_set(ASN1_STRING *x, int n);
-OPENSSL_EXPORT int ASN1_STRING_type(ASN1_STRING *x);
+OPENSSL_EXPORT int ASN1_STRING_type(const ASN1_STRING *x);
 OPENSSL_EXPORT unsigned char * ASN1_STRING_data(ASN1_STRING *x);
 OPENSSL_EXPORT const unsigned char *ASN1_STRING_get0_data(const ASN1_STRING *x);
 
 DECLARE_ASN1_FUNCTIONS(ASN1_BIT_STRING)
-OPENSSL_EXPORT int		i2c_ASN1_BIT_STRING(ASN1_BIT_STRING *a,unsigned char **pp);
+OPENSSL_EXPORT int		i2c_ASN1_BIT_STRING(const ASN1_BIT_STRING *a,unsigned char **pp);
 OPENSSL_EXPORT ASN1_BIT_STRING *c2i_ASN1_BIT_STRING(ASN1_BIT_STRING **a,const unsigned char **pp, long length);
 OPENSSL_EXPORT int		ASN1_BIT_STRING_set(ASN1_BIT_STRING *a, unsigned char *d, int length );
 OPENSSL_EXPORT int		ASN1_BIT_STRING_set_bit(ASN1_BIT_STRING *a, int n, int value);
-OPENSSL_EXPORT int		ASN1_BIT_STRING_get_bit(ASN1_BIT_STRING *a, int n);
-OPENSSL_EXPORT int            ASN1_BIT_STRING_check(ASN1_BIT_STRING *a, unsigned char *flags, int flags_len);
+OPENSSL_EXPORT int		ASN1_BIT_STRING_get_bit(const ASN1_BIT_STRING *a, int n);
+OPENSSL_EXPORT int            ASN1_BIT_STRING_check(const ASN1_BIT_STRING *a, unsigned char *flags, int flags_len);
 
 OPENSSL_EXPORT int		i2d_ASN1_BOOLEAN(int a,unsigned char **pp);
 OPENSSL_EXPORT int 		d2i_ASN1_BOOLEAN(int *a,const unsigned char **pp,long length);
 
 DECLARE_ASN1_FUNCTIONS(ASN1_INTEGER)
-OPENSSL_EXPORT int		i2c_ASN1_INTEGER(ASN1_INTEGER *a,unsigned char **pp);
+OPENSSL_EXPORT int		i2c_ASN1_INTEGER(const ASN1_INTEGER *a,unsigned char **pp);
 OPENSSL_EXPORT ASN1_INTEGER *c2i_ASN1_INTEGER(ASN1_INTEGER **a,const unsigned char **pp, long length);
 OPENSSL_EXPORT ASN1_INTEGER *	ASN1_INTEGER_dup(const ASN1_INTEGER *x);
 OPENSSL_EXPORT int ASN1_INTEGER_cmp(const ASN1_INTEGER *x, const ASN1_INTEGER *y);
@@ -713,15 +713,15 @@
 
 OPENSSL_EXPORT ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s,time_t t);
 OPENSSL_EXPORT ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s,time_t t, int offset_day, long offset_sec);
-OPENSSL_EXPORT int ASN1_TIME_check(ASN1_TIME *t);
-OPENSSL_EXPORT ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(ASN1_TIME *t, ASN1_GENERALIZEDTIME **out);
+OPENSSL_EXPORT int ASN1_TIME_check(const ASN1_TIME *t);
+OPENSSL_EXPORT ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(const ASN1_TIME *t, ASN1_GENERALIZEDTIME **out);
 OPENSSL_EXPORT int ASN1_TIME_set_string(ASN1_TIME *s, const char *str);
 
-OPENSSL_EXPORT int i2a_ASN1_INTEGER(BIO *bp, ASN1_INTEGER *a);
-OPENSSL_EXPORT int i2a_ASN1_ENUMERATED(BIO *bp, ASN1_ENUMERATED *a);
-OPENSSL_EXPORT int i2a_ASN1_OBJECT(BIO *bp,ASN1_OBJECT *a);
-OPENSSL_EXPORT int i2a_ASN1_STRING(BIO *bp, ASN1_STRING *a, int type);
-OPENSSL_EXPORT int i2t_ASN1_OBJECT(char *buf,int buf_len,ASN1_OBJECT *a);
+OPENSSL_EXPORT int i2a_ASN1_INTEGER(BIO *bp, const ASN1_INTEGER *a);
+OPENSSL_EXPORT int i2a_ASN1_ENUMERATED(BIO *bp, const ASN1_ENUMERATED *a);
+OPENSSL_EXPORT int i2a_ASN1_OBJECT(BIO *bp, const ASN1_OBJECT *a);
+OPENSSL_EXPORT int i2a_ASN1_STRING(BIO *bp, const ASN1_STRING *a, int type);
+OPENSSL_EXPORT int i2t_ASN1_OBJECT(char *buf,int buf_len, const ASN1_OBJECT *a);
 
 OPENSSL_EXPORT ASN1_OBJECT *ASN1_OBJECT_create(int nid, unsigned char *data,int len, const char *sn, const char *ln);
 
@@ -732,9 +732,9 @@
 OPENSSL_EXPORT BIGNUM *ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai,BIGNUM *bn);
 
 OPENSSL_EXPORT int ASN1_ENUMERATED_set(ASN1_ENUMERATED *a, long v);
-OPENSSL_EXPORT long ASN1_ENUMERATED_get(ASN1_ENUMERATED *a);
-OPENSSL_EXPORT ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(BIGNUM *bn, ASN1_ENUMERATED *ai);
-OPENSSL_EXPORT BIGNUM *ASN1_ENUMERATED_to_BN(ASN1_ENUMERATED *ai,BIGNUM *bn);
+OPENSSL_EXPORT long ASN1_ENUMERATED_get(const ASN1_ENUMERATED *a);
+OPENSSL_EXPORT ASN1_ENUMERATED *BN_to_ASN1_ENUMERATED(const BIGNUM *bn, ASN1_ENUMERATED *ai);
+OPENSSL_EXPORT BIGNUM *ASN1_ENUMERATED_to_BN(const ASN1_ENUMERATED *ai,BIGNUM *bn);
 
 /* General */
 /* given a string, return the correct type, max is the maximum length */
@@ -753,7 +753,7 @@
 #ifndef OPENSSL_NO_FP_API
 OPENSSL_EXPORT void *ASN1_item_d2i_fp(const ASN1_ITEM *it, FILE *in, void *x);
 OPENSSL_EXPORT int ASN1_item_i2d_fp(const ASN1_ITEM *it, FILE *out, void *x);
-OPENSSL_EXPORT int ASN1_STRING_print_ex_fp(FILE *fp, ASN1_STRING *str, unsigned long flags);
+OPENSSL_EXPORT int ASN1_STRING_print_ex_fp(FILE *fp, const ASN1_STRING *str, unsigned long flags);
 #endif
 
 OPENSSL_EXPORT int ASN1_STRING_to_UTF8(unsigned char **out, ASN1_STRING *in);
@@ -764,12 +764,12 @@
 OPENSSL_EXPORT int ASN1_GENERALIZEDTIME_print(BIO *fp, const ASN1_GENERALIZEDTIME *a);
 OPENSSL_EXPORT int ASN1_TIME_print(BIO *fp, const ASN1_TIME *a);
 OPENSSL_EXPORT int ASN1_STRING_print(BIO *bp, const ASN1_STRING *v);
-OPENSSL_EXPORT int ASN1_STRING_print_ex(BIO *out, ASN1_STRING *str, unsigned long flags);
+OPENSSL_EXPORT int ASN1_STRING_print_ex(BIO *out, const ASN1_STRING *str, unsigned long flags);
 OPENSSL_EXPORT const char *ASN1_tag2str(int tag);
 
 /* Used to load and write netscape format cert */
 
-OPENSSL_EXPORT void *ASN1_item_unpack(ASN1_STRING *oct, const ASN1_ITEM *it);
+OPENSSL_EXPORT void *ASN1_item_unpack(const ASN1_STRING *oct, const ASN1_ITEM *it);
 
 OPENSSL_EXPORT ASN1_STRING *ASN1_item_pack(void *obj, const ASN1_ITEM *it, ASN1_OCTET_STRING **oct);
 
@@ -793,8 +793,8 @@
 OPENSSL_EXPORT int ASN1_item_i2d(ASN1_VALUE *val, unsigned char **out, const ASN1_ITEM *it);
 OPENSSL_EXPORT int ASN1_item_ndef_i2d(ASN1_VALUE *val, unsigned char **out, const ASN1_ITEM *it);
 
-OPENSSL_EXPORT ASN1_TYPE *ASN1_generate_nconf(char *str, CONF *nconf);
-OPENSSL_EXPORT ASN1_TYPE *ASN1_generate_v3(char *str, X509V3_CTX *cnf);
+OPENSSL_EXPORT ASN1_TYPE *ASN1_generate_nconf(const char *str, CONF *nconf);
+OPENSSL_EXPORT ASN1_TYPE *ASN1_generate_v3(const char *str, X509V3_CTX *cnf);
 
 
 #ifdef  __cplusplus