diff --git a/Cargo.lock b/Cargo.lock
index ab64742..8f33a3a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -63,7 +63,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1d2838fdd79e8776dbe07a106c784b0f8dda571a21b2750a092cc4cbaa653c8e"
 dependencies = [
  "funty",
- "radium",
+ "radium 0.4.1",
+ "wyz",
+]
+
+[[package]]
+name = "bitvec"
+version = "0.19.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7ba35e9565969edb811639dbebfe34edc0368e472c5018474c8eb2543397f81"
+dependencies = [
+ "funty",
+ "radium 0.5.3",
+ "tap",
  "wyz",
 ]
 
@@ -168,7 +180,19 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e66558629d772c3be040566b7be07be8c8f5aecee95e4a092dfe2efc313277ad"
 dependencies = [
- "nom",
+ "nom 5.1.2",
+ "num-bigint 0.3.0",
+ "num-traits",
+ "proc-macro-hack",
+]
+
+[[package]]
+name = "der-oid-macro"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd17d13ecf875e704369fdbde242483ac769fc18f6af21e43d5a692a079732fc"
+dependencies = [
+ "nom 6.0.1",
  "num-bigint 0.3.0",
  "num-traits",
  "proc-macro-hack",
@@ -180,12 +204,26 @@ version = "4.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "caca07c50eaae94d43e21f4d14eca5543b6f5f5ce64715e9b7665ac5f5185b4e"
 dependencies = [
- "der-oid-macro",
- "nom",
+ "der-oid-macro 0.2.0",
+ "nom 5.1.2",
  "num-bigint 0.3.0",
  "num-traits",
  "proc-macro-hack",
- "rusticata-macros",
+ "rusticata-macros 2.1.0",
+]
+
+[[package]]
+name = "der-parser"
+version = "5.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb4b1e27396f46037881c39d821660f2ff48797aaa7152a45ded7a93b368a819"
+dependencies = [
+ "der-oid-macro 0.3.0",
+ "nom 6.0.1",
+ "num-bigint 0.3.0",
+ "num-traits",
+ "proc-macro-hack",
+ "rusticata-macros 3.0.1",
 ]
 
 [[package]]
@@ -214,7 +252,7 @@ version = "0.6.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "396db09c483e7fca5d4fdb9112685632b3e76c9a607a2649c1bf904404a01366"
 dependencies = [
- "bitvec",
+ "bitvec 0.18.4",
  "const-oid",
  "ff",
  "generic-array",
@@ -242,7 +280,7 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "01646e077d4ebda82b73f1bca002ea1e91561a77df2431a9e79729bcc31950ef"
 dependencies = [
- "bitvec",
+ "bitvec 0.18.4",
  "rand_core",
  "subtle",
 ]
@@ -399,6 +437,18 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "nom"
+version = "6.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "88034cfd6b4a0d54dd14f4a507eceee36c0b70e5a02236c4e4df571102be17f0"
+dependencies = [
+ "bitvec 0.19.4",
+ "lexical-core",
+ "memchr",
+ "version_check",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.2.6"
@@ -470,6 +520,15 @@ dependencies = [
  "autocfg 1.0.1",
 ]
 
+[[package]]
+name = "oid-registry"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2508c8f170e55be68508b1113956a760a82684f42022f8834fb16ca198621211"
+dependencies = [
+ "der-parser 5.0.0",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.5.2"
@@ -587,6 +646,12 @@ version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "64de9a0c5361e034f1aefc9f71a86871ec870e766fe31a009734a989b329286a"
 
+[[package]]
+name = "radium"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "941ba9d78d8e2f7ce474c015eea4d9c6d25b6a3327f9832ee29a4de27f91bbb8"
+
 [[package]]
 name = "rand"
 version = "0.7.3"
@@ -689,7 +754,16 @@ version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8a9050636e8a1b487ba1fbe99114021cd7594dde3ce6ed95bfc1691e5b5367b"
 dependencies = [
- "nom",
+ "nom 5.1.2",
+]
+
+[[package]]
+name = "rusticata-macros"
+version = "3.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7390af60e66c44130b4c5ea85f2555b7ace835d73b4b889c704dc3cb4c0468c8"
+dependencies = [
+ "nom 6.0.1",
 ]
 
 [[package]]
@@ -817,6 +891,12 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "tap"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "36474e732d1affd3a6ed582781b3683df3d0563714c59c39591e8ff707cf078e"
+
 [[package]]
 name = "termcolor"
 version = "1.1.2"
@@ -1022,12 +1102,32 @@ dependencies = [
  "base64 0.13.0",
  "chrono",
  "data-encoding",
- "der-oid-macro",
- "der-parser",
+ "der-oid-macro 0.2.0",
+ "der-parser 4.1.0",
  "lazy_static",
- "nom",
+ "nom 5.1.2",
  "num-bigint 0.3.0",
- "rusticata-macros",
+ "rusticata-macros 2.1.0",
+ "rustversion",
+ "thiserror",
+]
+
+[[package]]
+name = "x509-parser"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b22c80f083d860f8e77f44762e9df8c92de7defeb70219ec37f32968cab53e90"
+dependencies = [
+ "base64 0.13.0",
+ "chrono",
+ "data-encoding",
+ "der-oid-macro 0.3.0",
+ "der-parser 5.0.0",
+ "lazy_static",
+ "nom 6.0.1",
+ "num-bigint 0.3.0",
+ "oid-registry",
+ "rusticata-macros 3.0.1",
  "rustversion",
  "thiserror",
 ]
@@ -1043,7 +1143,7 @@ dependencies = [
  "sha2",
  "subtle-encoding",
  "termcolor",
- "x509-parser",
+ "x509-parser 0.8.2",
  "yubikey-piv",
 ]
 
@@ -1053,7 +1153,7 @@ version = "0.1.0"
 dependencies = [
  "chrono",
  "cookie-factory",
- "der-parser",
+ "der-parser 5.0.0",
  "des",
  "elliptic-curve",
  "env_logger",
@@ -1061,7 +1161,7 @@ dependencies = [
  "hmac",
  "lazy_static",
  "log",
- "nom",
+ "nom 6.0.1",
  "num-bigint-dig",
  "num-integer",
  "num-traits",
@@ -1077,7 +1177,7 @@ dependencies = [
  "subtle",
  "subtle-encoding",
  "x509",
- "x509-parser",
+ "x509-parser 0.9.0",
  "zeroize",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 2d06602..cdb106e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,13 +24,13 @@ maintenance = { status = "experimental" }
 [dependencies]
 chrono = "0.4"
 cookie-factory = "0.3"
-der-parser = "4"
+der-parser = "5"
 des = "0.6"
 elliptic-curve = "0.6"
 getrandom = "0.1"
 hmac = "0.10"
 log = "0.4"
-nom = "5"
+nom = "6"
 num-bigint = { version = "0.6", features = ["rand"], package = "num-bigint-dig" }
 num-traits = "0.2"
 num-integer = "0.1"
@@ -45,7 +45,7 @@ sha2 = "0.9"
 subtle = "2"
 subtle-encoding = "0.5"
 x509 = "0.1.2"
-x509-parser = "0.8"
+x509-parser = "0.9"
 zeroize = "1"
 
 [dev-dependencies]
diff --git a/src/certificate.rs b/src/certificate.rs
index 9412079..1d0bc35 100644
--- a/src/certificate.rs
+++ b/src/certificate.rs
@@ -49,7 +49,7 @@ use sha2::{Digest, Sha256};
 use std::convert::TryFrom;
 use std::fmt;
 use std::ops::DerefMut;
-use x509_parser::{parse_x509_der, x509::SubjectPublicKeyInfo};
+use x509_parser::{parse_x509_certificate, x509::SubjectPublicKeyInfo};
 use zeroize::Zeroizing;
 
 use crate::CB_OBJ_MAX;
@@ -205,7 +205,13 @@ impl PublicKeyInfo {
             }
             OID_EC_PUBLIC_KEY => {
                 let key_bytes = &subject_pki.subject_public_key.data;
-                match read_pki::ec_parameters(&subject_pki.algorithm.parameters)? {
+                let algorithm_parameters = subject_pki
+                    .algorithm
+                    .parameters
+                    .as_ref()
+                    .ok_or(Error::InvalidObject)?;
+
+                match read_pki::ec_parameters(algorithm_parameters)? {
                     AlgorithmId::EccP256 => EcPublicKey::from_bytes(key_bytes)
                         .map(PublicKeyInfo::EcP256)
                         .map_err(|_| Error::InvalidObject),
@@ -471,7 +477,7 @@ impl Certificate {
             return Err(Error::SizeError);
         }
 
-        let parsed_cert = match parse_x509_der(&cert) {
+        let parsed_cert = match parse_x509_certificate(&cert) {
             Ok((_, cert)) => cert,
             _ => return Err(Error::InvalidObject),
         };
@@ -631,12 +637,7 @@ mod read_pki {
     /// }
     /// ```
     pub(super) fn ec_parameters(parameters: &DerObject<'_>) -> Result<AlgorithmId, Error> {
-        let curve_oid = match parameters.as_context_specific() {
-            Ok((_, Some(named_curve))) => {
-                named_curve.as_oid_val().map_err(|_| Error::InvalidObject)
-            }
-            _ => Err(Error::InvalidObject),
-        }?;
+        let curve_oid = parameters.as_oid_val().map_err(|_| Error::InvalidObject)?;
 
         match curve_oid.to_string().as_str() {
             OID_NIST_P256 => Ok(AlgorithmId::EccP256),